I wouldn't call the Venture a low-tech carrier however, for starters it's not a dedicated carrier and for another it's more of a civilian vessel.
To me, the Venture feels like a military ship that the military decided they didn't need and which they therefore permitted to be used for civilian purposes, rather than being a civilian ship from the start. It feels a lot like the compromise cruiser/carrier hybrids that were experimented with in the real world and soon discarded in favor of dedicated carriers with dedicated escorts - a ship with inadequate firepower for its size, if it's to be used in the battle line, and a carrier with inadequate fighter capacity if it's to be used in the support role that dedicated carriers fill. In short, a flawed concept that is nevertheless useful as a combat-capable civilian vessel.
I think the number of hangar decks is highly disparate, currently. The Astral has 6 decks and the next best carrier, the Heron, has 2. That does not add up.
I think the Condor should have 2 decks to distinguish it more from the Gemini. It's kind of ridiculous that the Gemini is nearly as good a cargo ship as a Tarsus, and just as good a carrier as a Condor. But if the Condor got extra decks, then the ships above it with decks should get more, too. The Venture, Atlas, and (maybe) the Odyssey should have 2 decks, and the Heron, being a cruiser-sized Fast Carrier, should have 3 decks.
I disagree with the Condor receiving two flight decks if the Gemini sticks with only one. In my opinion, the Gemini feels much more like a purpose-built military escort carrier than the Condor does, with a significantly better defensive armament, a military-grade shield generator for a mid-tech vessel, and fairly decent flux stats given its armament. The only part about it that says "I'm not a military ship" is its description, but even if that doesn't change, it would hardly be unique in history for a military vehicle to be misrepresented in this way. If either of the light carriers is to receive a second flight deck, my feeling is that it should be the Gemini.
That said, I also disagree with either of the light carriers receiving an additional flight deck, as unless the second flight deck comes with an increase in logistical costs sufficient to cause the light carrier to count for about as much as a cruiser in the fleet, the two-deck light carrier will be by far the most logistically-efficient carrier available, with a flight deck for roughly 2.75 logistics. Compare this to the Astral, the most logistically-efficient carrier currently, which costs at least 3.625 logistics per flight deck (3.917 logistics per flight deck with standard skeleton crew). The way it works now is fairly good - if you buy a bigger carrier, you pay more logistics per carrier and have a generally more expensive carrier (in terms of absolute purchase costs, absolute operating costs, and absolute deployment costs; deployment cost relative to the number of flight decks deployed is a slightly different matter, as the Heron is the least efficient at 18 supplies per flight deck, but the Gemini and the Condor are tied for most efficient at 10 supplies per flight deck, which is much better than the Astral's 16.7 supplies per flight deck) and lose more if you lose that carrier, but you gain logistical efficiency, durability, and perhaps firepower. Giving a light carrier two flight decks greatly changes the question of logistical efficiency and takes away one of the only real reasons to use a larger dedicated carrier, unless there are changes to the logistical costs of or the number of flight decks on all the carriers in the game.
Also, from a logistical efficiency perspective, the Gemini is a significantly worse freighter than the Tarsus is, as the Tarsus carries at least 2.65 times more cargo per logistics unit. This isn't nearly as bad as the Condor, which carries nearly 2.2 times less cargo per logistics unit than the Gemini does, but it's still not a good freighter from a fleet efficiency perspective. The Gemini also isn't a particularly efficient freighter in terms of operating cost efficiency, as it carries only ~70% of the cargo of the Tarsus per supply expended per day of noncombat and nonrecovery operations.
Since the Condor is a stripped down Tarsus, making it go faster is not unreasonable.
I disagree with describing the Condor as a stripped-down Tarsus. The Condor is a heavily-modified Tarsus, having gained a completely new weapons mount in a location where there previously was no weapons mount and having had a fairly significant amount of hull reinforcement, as well as receiving significantly improved armor. A stripped-down Tarsus would be more along the lines of the Tarsus you purchase from the shipyard - a hull with the essential equipment intact, but carrying more or less nothing else.
This would take things from Destroyer: 1, 1; Cruiser: 1, 2; and Capital: 1, 1, 6; to Destroyer: 1, 2; Cruiser: 2, 3; and Capital: 2, 2, 6 (1, 2, 6 if the Odyssey stays at 1 deck). I imagine a Cruiser-sized dedicated carrier and a Capital-sized Fast Carrier would both get 4 decks. A Destroyer-sized Fast Carrier would of course only have one deck. So with those three hypothetical ships included in this change, there would be Destroyer: 1, 1, 2; Cruiser: 2, 3, 4; and Capital: 2, 2, 4, 6 (or 1, 2, 4, 6).
I think you really need to take logistical efficiency into account, as it and durability and perhaps firepower are all that the larger carriers have going for them, and a carrier's firepower can largely be replaced by well-managed fighter wings, especially since carriers tend to want to stay out of fights with anything approaching their own weight class.
Flight Decks per Logistics Unit
Carrier Efficiency (Half Skeleton) Efficiency (Standard Skeleton) Efficiency (Max Crew)
Condor 5.330 5.650 6.50
Gemini 5.180 5.350 6.20
Heron 4.875 5.250 5.75
Astral 3.625 3.917 5.00
As you can see from the table, any destroyer-scale carrier that carries two flight decks is either going to have to have such terrible statistics as to be useless to a fleet (e.g. burn-2, consistently loses fights against lone asteroids, etc) or is going to cost something more appropriate for a cruiser - a minimum of ~7 logistics if you want it to stay roughly in line as a flight deck provider with the Astral, which is already about what a medium cruiser like an Eagle costs - if you don't want it to significantly outclass existing dedicated carriers as a supporting flight deck for your fleet. A cruiser-scale carrier with three flight decks is going to have to cost in the neighborhood of 11 or 12 logistics to avoid outclassing the Astral as a dedicated carrier, and maybe a little more to avoid outclassing the Heron - though since the Heron is already an unusually fast cruiser both in and out of combat and has an armament that could let it work as a (very) light cruiser, there's a bit more room to play with logistical efficiency than there is with the destroyer-scale carriers, which are slow in combat and of typical speed outside combat and lack the combat power to take on most dedicated warships without escorts or a good pilot. A four deck cruiser-scale carrier is going to have to cost in the neighborhood of 15 logistics to avoid outclassing the Astral as a dedicated carrier, which borders on what a capital ship costs.
