Gordon, that’s a cool camera. I restored an original Art Deco Rolleicord, a few years older than yours. They are still great users 90 years later.
FWIW, it’s probably not worth the effort to worry about small bits of fungus on the viewing lens. Obviously, it will not affect the negatives. If the viewfinder is dim, that is much more likely to be caused by surface loss on the mirror behind the viewing lens that reflects light up to the screen. Most of these early Rolleicords have problems with desilvering of that mirror. Replacements are inexpensive and easily sourced. See, e.g.,
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A mirror replacement will make the camera much more useable. Modern viewscreens are also much brighter than the originals, but some users prefer the original ground glass finders.
Good luck with your new camera!