Highest Level achieveable with regifts and mislabelled free or beta keys

mostly lvl 1

I saw a lvl3

Considering most free games are bundled keys at less than €10 store value (and thus at most €1.5 CV each) You'd have to get away with succesfully giving 15-20 of them just to reach level 2. If you do it in a batch you're bound to get noticed before it ends and otherwise you'll probably be found out anyway over time.
It does require manual reporting though and sometimes support takes a while to follow up so its not impossible to get higher, but either way you're going to get it revoked anyway and at the early levels the advantages of temporarily cheating the system is negligible (it's barely ever existent at any level).

I've seen L2 myself, ONLY mislabelled games, beta keys and free games (for some reason not removed).

unless support makes stats visible, we don't know anything...

regifts and free GAs are deleted, and giveaways where the winner gets something else will be marked as not received. they won't give any cv.

some people cheat anyway, but they will caught at some point.