... a new system where if you attack a fleet from the right you should spawn on the left side of the map according to what direction you are attacking the enemy and they would deploy on the side relative to your fleet when the encounter was made...
iirc something along these lines was proposed some time in the past, and the eventual response was that it wouldn't really add anything beneficial to the combat experience.
Combat is "upwards" facing for a reason, it makes it easy to orient that you are always going "forwards" towards the enemy.
A way to consider it is that "up" is not north, "up" is instead towards the enemy fleet, and the battle map is pre-rotated to take this into account so you always have a nice upwards combat orientation, rather than at some random angle.
And i think the whole idea of being able to "flank" an enemy and attack their fleet from the side doesn't make much sense, with the time it takes to get into shooting range after a battle starts, even if you had something as sluggish as a paragon, you'd be able to turn to face the enemy long before they get into range, making the "advantage" of flanking a moot point.
It would only really start to make any sense if you are engaging with an already occuring battle. Which is the one instance where I could see being able to deploy from the sides be an actual interesting (and logical) addition to gameplay.