Hmm...seems that the stratum job delivery works well, but submitting a found block makes errors in my stratum:
ERROR: rpc_do_call: coind:28443 500
ERROR LemonCoin Invalid mode
*** REJECTED :( LemonCoin block 147014 1 txs
Investigating the issue, all other argon2 coins works on my pool, this makes no sense at all to me if this coin's source is forked from any of those.
I'll gladly host a LEMON pool if I find the solution.