I found a good-looking Fuji GS645S save for two small issues. Can I fix tiny lens fungus & a tiny bit of haze? (If that's what this actually is.)

I replaced Fuji 645 with a Zeiss Ikon Super Ikonta A...bellows, at least 70 yrs old but in perfect condition. I never bothered with Fuji’s meter.
So far I haven’t heard of any bellows problems for my GF670. Keeping my fingers crossed.
I would put forth the idea that plastic was much cheaper, and reducing weight was an after thought promoted by advertisement department.