I have just reached a total number of 242 levels of Mechan General Enhancement.
As it is stated,
The class bonuses as General increase with each level. All bonuses increase except: • Small chance to immediately destroy a Deathstar once in a battle using a light fighter • Wreckage at attack (transport to starting planet) • Detailed fleet speed settings • Discount on acceleration (shipyard)
So, in this case speed for combat ships increases, deut consumption for ships decreases and cargo bay for some ships increase.
What also increased is fleet slot and combat research level and moon fields. That is good for me. Fleet slot was 37 and it became 38. Combat research levels also increased +1
However, this increase happens in only Mechas planets even though I have Mechan General Enhancement in Human, Kaelesh and Rock'tal planets.
Let me show with screenshots from different planets.
I think enhancement should apply to all planets as it does for other enhancements such as deut consumption reduction, ship cargo increase etc.
I think it is a bug.