From what i peeked at the japanese wiki (just images and numbers i don't understand the text), from map 5 to 8 mobs stay in the 40~ range, including bosses.

It might be scary depending on whose those 40 lv monsters are, map 3 or 4 had a lvl 40 'slug yuu', which is really doable, as they seem easier than other mobs like 'slugs me'.

Anyway, maps 7 and 8 seem kinda nasty due to either being long with bugs or having 3 bosses to kill. Seems like map 8 will also require being able to create parties of different speeds as there are 3 path with different lenghts. I hope i can train my team fast enough for the end of the event. I only had 1-2 hours per day last week, so no endless farming was done and i'm still at 36k-26k-19k-19k.

So i guess almost everyone currently playing will get to 22, but 3 starring 7 and 8 might be kkinda hard if you couldn't/ haven't farme for quite some days.