So here's my results so far.

-25 stages of PoC gave me 1219 feathers + 216 x 6 = 1296 feathers from invasions, 2515 total; estimated 26667 feathers by the end of the event;
-1st event tile lvl 37 (lieutenant lvl 47);
-Cleared 8 event tiles (32 stages), got 5 corns so far (stage 1 (tile 1 map 1), stage 3 (til 1 map 3), stage 22 (tile 6 map 2), stage 26 (tile 7 map 2), stage 28 (tile 7 map 4));
-Lost a couple tanks here and there, mostly because of wrong skill/deploy timings.

Overall seems not very hard event (at least for me), both 5*s from previous event are very useful here. Early maps has enough holes in enemy defenses and weak commanders so rush with satan works perfect there, later has heavier defense and tanky commander so panzerwaifu really helpful.