Bolt 373 is originally glued - it is now very hard to tell why you can’t remove the bolt.
Either it is just the glue still holding the bolt - or, that would be dangerous, maybe there is rust in the thread. You are now of course in danger to break the bolt…that would be pretty bad because in that case has the complete axle to be replaced (that again means complete disassembly of the rear part).
I would now try to heat up the bolt’s head a little bit, not with flame but with electric heat gun.
There is no other way than that of removing 373 first - it is impossible to get “from the other side” because the axle (at the same time axle stump below 373) goes through the bottom tube.