I think Foehn needs nerfing and tweaking though that's just me.
It's not just you, there are tons of other people asking for nerfs on Foehn. Hopefully the devs are listening as I'm sure they will come to realise that it definitely needs to be brought down to earth. For example, try beating Wings Of Coronia as Confed. - They will get completely slaughtered. Maybe pro-level Confed players could win but it's definitely not balanced and whilst I am thankful for the new faction the MO team have blessed us with, it has thrown all the other factions out of balance - at least in the current update.
There always been sub-factions that is strong against some and weak against some, since each sub-faction has their own pros and cons which can be taken advantage by other sub-faction cons and pros.
If you're playing with a sub-faction that's apparently weak against your enemy's sub-faction on purpose, that's just you asking to have more difficulty.
If you got matched with a sub-faction that would eat you alive without knowing, that's just your luck.
If you're asking for all to be balanced, then all sides will have no weakness/strong points which give them uniqueness.
Weakness/Strong points such as have superior AA but have little to no siege. Have very high mobility but weak firepower. Have precision strikes but only work on specific target type. Etc.
Foehn themselves have weaknesses.
Space (larger power plant), slow starting money plus weak individual miners, no unit to detect + kill spies, other than Wings of Coronia, the other 2 don't really have strong air units to go against armor/infantry type. Difficulty to infiltrate. Their basic AA allows jets to drop their payloads before getting destroyed.