I think you didnt consider some things regarding balance.
You cant just give an entire faction speed or damage. Balance needs to exist in every category for any match up or 1v1 is simply unplayable. You cant just give air units of one factions more speed and then say "well they are just better at that".
Sure there are units that are better than others but a faction needs to have some kind of answer to things. One faction having more speed on their asf would be massively busted and playing that faction for air would be the meta.
But if you do want to do something like this yourself you can check out my casino mod (to see how its done) which uses unit buffs such as health, speed and damage


