Haven't played a Metelson campaign yet, but i still tested a few things. I noticed a few issues here and there. The faction could use a balance pass, and some descriptions have really weird writing. I also have a few issues with the Metelson-ised vanilla sprites.
The first simple thing i noticed, would be to rename the mod folder. "miPUBLIC" isn't really telling, a zip/folder named "Metelson" with the version number would be easier to manage for the player.
In the campaign, there's no description when hovering the mouse over MiShip Port in Corvus. As for the descriptions, there's quite a few weird ones. I won't list all of them, but the issue is quite obvious in Nemo's video (around 31:50).
https://youtu.be/k9Yn9OXieDg?t=30m50sFor the ships, i noticed Metelson crafts were always superior to their vanilla equivalent, sporting slightly better stats/mounts, for the same cost (Stinulv/Wolf, Mite/Kite, Farin/Cerberus, etc.). While there are some blatantly stronger ships (Actel, Varingur, Acutor...), they only really are because of their extremely cheap deployment price. The rest of the fleet tends to be more reasonable with the balance, although i just skimmed over them with the simulator, so i could have missed some things.
I have a gripe with the Rostor system series. I think there's 3 of those, all of them offers just slightly different stats but otherwise looks nearly identical to each other (and to their vanilla cousin, the Damper field). This is also part of what i think is the biggest issue with the mod : readability. You can't quickly identify who does what in a Metelson fleet, this includes ship systems and the Metelson/Vanilla variants. The video i posted above also highlight this problem, Nemo cannot immediately differentiate the Metelson ships from vanilla.
Here's what i did for the Custos, AKA Enforson :
Asides from the mounts and color, the Custos is pretty much a carbon-copy of the Enforcer XIV. On the right, i tried to Metelson-ize it while keeping the original shape. Other mods like Tiandong and the Ship/weapon pack offer a good execution of the whole "vanilla ship, but different" idea if you need some guidelines.
While this is not in-depth feedback, i hope this'll still be helpful for improving your faction.