>>Well, let's see. nadir is the opposite of peak, so "even for a native snadirer" would be the opposite of "even for a native speaker". If we want to convey the same intention, we have to negate "even for native snadirer". So, either, "even for a non native snadirer", or maybe "not even for a native snadirer". Or perhaps "even for a native non snadirer".
>
>Or "uneven for..."?

Hmmm... reverse a whole word? Seems like cheating somehow. ;)

How about instead, "even fand a native snadirer." Or maybe "even for a natyouve snadirer." Or better yet, "even fand a non natyouve snadirer."

Can you imagine holding an actual verbal conversation like that? There would certainly be no such thing as a short confab.