since she's using it as a name, for me at least, it souds better to say "hentai-san" than saying "pervert-san" it's not a problem of "it's hard to translate", it's more of "what sounds better"(imo)
iirc, it was explainded on earlier chapters, but i believe it means that his current lvl is 9 in this try, while his total lvl is 38 combining all the others times he died