In the generous interpretation of 'middle'. Ukrainian reports tend to be a lot closer to the truth than Russian reports, but they do still have some bias (as in it's rare that things are better then Ukraine is making out).
Sure. But the solution isn't to interpolate Russian and Ukraininan claims, as the former have been proven time and again to be complete fabrications. Instead, a good M.O. is to take Ukraininan claims with a grain of salt until corroborated by either open-source or third-party analysis.
The real marker is immediate numbers. I bet even Russians yet to find out how many aircrafts have they irrecoverably lost, however we get numbers reported as if they are confirmed.
Cheap