I played P4 “the golden” in Japanese, not P5 yet, but if the difficulty level is roughly similar I’d give it something like L28~30 on Natively. As far as JRPGs go, it’s definitely not on the easier side, in my experience mainly because it actually takes place in Japan and not a made up fantasy world. So you have to deal with all the intricacies of “real” Japanese: slang, dialect, cultural references etc… The ratio of text-to-gameplay is also very lopsided, there’s a ton of dialogue to go through.
But honestly if you know the game well and are motivated I wouldn’t worry about that. The very first piece of native Japanese content I really engaged with was Final Fantasy VIII back when I was absolutely not up to the level required to play such a game and I still managed to make it work with a ton of patience, lookups, checking with the English version when I was completely lost etc…
Yeah that’s absolutely normal. I play a lot of games in Japanese and I can do that fairly casually these days but from time to time a character will pop up that speaks in a very peculiar dialect and suddenly I have to spend 30 seconds on every sentence…
Be careful not to overdo it, if you just log every word you have to look up you’re going to log a lot of stuff. I tend to wait until I encounter a word a few times before I decide to create an Anki card.
I also have an arbitrary rule where I decided that I would only add max one word per scene/conversation. Otherwise I find that it breaks the flow too much. Learning to deal with ambiguity and partial understanding is actually a useful skill to develop too, sometimes you have to go with the flow.