Do the long range units still backpedal?
Yes, they do. If unit can use range advantage - unit should use it.
I think you'll find some huge balance issues caused by the changed to range. For example, if Reapers stay at the maximum attack range they are unkillable wby the short range Zeus.
I played a last mission in Genesis campaign and a few skirmishes. And I had no problem with unkillable ranged units. Maybe because I knew about new unit behavior and didn't used short ranged units alone. Only mixed with ranged units. In this case short ranged units became kind of damage soakers*, but ranged usually survive and provide firepower.
I agree that single Zeus vs singe Reaper will loose, but such situations are rare in battlefield.
*therefore they need HP and shield buff. I believe 30% will be ok, but I need to test it.
We are looking into a fix for this, like making it so backpedalling in combat has a much lower movement speed or none at all.
None is too much. But 30 - 50 percents slower will be ok. You can use modern armored vehicles as example.
||71 km/h; backwards 31 km/h