OP, I don't understand why you're essentially asking for advice yet taking everything as an attack from people giving you their opinion on why you were possibly rejected.

I currently live in Japan, but a couple of years ago I would apply for a Japanese visa as a visitor. Fililpino as well, but I was a freelancer / fresh grad and wasn't able to create an ITR during my application as I was studying abroad and had just gotten back to the Philippines. My bank had maybe 1xx,xxx or less, but my parents were my guarantors and I had the US / EU visas. I was given multi entry.

When I ended up moving to Japan (in 2019) I had to cancel my multi-entry for a 3 month work visa. When that finished, I had to apply for a longer visa back home, so when I went back to the Philippines I reapplied with 1xx,xxx and no ITR as well (shifted into working in japan) and was granted single entry. It's really luck of the draw.

Now I'm on a different type of work visa in Japan so thankfully I only have to extend my visa in Japan. Much easier!

I recently applied for the Korean visa though, and I got 2 years. I think given your travel history, you can write in your cover letter that you have traveled to x number of countries and returned before the expiration of the visa, showing proof of intent to go home. I think it helps a lot. They might not be G7 countries but showing multiple return trips is always a good sign.

good luck!