I'd change power scale. Make characters more OP. Since leveling up is pretty hard and you need real challenges to level up. As example Level 7 would be mountain level. level 9 is continent tier and characters strong like Albert or Black dragon would be world tier.

Edit: And more feats like other anime characters. Danmachi people lacks that

It is far too late to do this they usually don’t rewrite unless something serious happened on the plot.

I suggest to read about the life of these Authors they dedicate considerable time and resources to their craft.

Authors also work on a set deadline by the publisher they must write their story at a set time.

Manga writing and Light novels is quite stressful they really push you into finishing.