Review Detail of TangyChili in Grandpa Universe In Multiverse [COMPLETE]

This is my first review so may be bad, take it with a grain of salt. Anyway, let's start with the plot. This is a fan-fiction, multiverse, isekai, with op MC novel. The story is about an old man who died and then went to become God's Advocate because all the good deeds he's done. His job is to basically kill bad people and make each world he visits better. The writing quality is pretty decent, but there are some typos and grammar errors every now and then , however there aren't times where the author messed up names or pronouns. Basically it's still understandable. The stability of updates (from what I've seen) is pretty good the author gives us 2 chapters a day. Story development: I found the story quite enjoyable it has it's hints of romance, it's a wholesome story, no harem, but there are many non canon couples (in each respective universe). There are 4 major worlds, as of now, Harry Potter, GoT, Avengers and One Piece. This is the main reason I decided to write this review, personally I've never seen Harry Potter, GoT, nor Avengers, and I still found enjoyment out of reading it. The author does a decent job at explaining some backstory so you aren't lost. I just read it as if the MC went to other generic fantasy worlds. However, I did do some research on characters to see a bit of their personal lore. Character design, I mean it's a more unique take on the isekai genre, with the MC being an old man, but still, it's an isekai with an OP MC, so you can't expect much. Also, since it's a fan-fiction many characters are just from pre-existing universes, but the author doesn't fiddle with their personalities much. World background, same as before since it's a fan-fiction I can't say much about it.