I don't know about your 1st statement if PoW mining is possible or not,
I did just try setgenerate true 4 in the console and it did not work to generate a PoW block,
if there are more commands, please share.
Your line 2 is totally wrong, PoS & PoW difficulty are not shared among any coin, they can't be , there are two independent ways to generate coins.
Same issue with the block freezing happened with PHS a few weeks ago, no big deal , as more blocks are available for staking the network returns to normal speed.
I still think that blockchain accept PoW blocks, however i missed that GetLastBlockIndex in this coin account on whether block is PoS or PoW. My mistake.
I will delete my previous message because it's partially untrue.
Your totally wrong about things here
Here is comparison of CBlock::AcceptBlock between standart codebase abd yours.
https://www.diffchecker.com/mc8jqidu
Left is yours.
You deleted check for Last_Pow_Block there. Where did wallet restrict PoW blocks?