Just read through the whole thread, matches my personal experience. Comments:

1. Easiest way of separating any lens group, whether Canada Balsam or any lens cement I've ever encountered, is old furniture stripper (MEK-based). Hard to find, I scour flea markets for old cans.

2. Centering most lens groups is easy with a flat surface and a pair of machining V-blocks.

3. If you can't find UV-cure optical cement (I ordered mine off AliExpress), clear-coat UV-cured nail polish is a good substitute, available at any nail salon.

4. The only reason to polish off surface etching from fungus is if you plan to sell the lens, IMHO, and if it's a coated lens and you polish off the coating to make it look pretty, you might get a better price for your lens but it's a little unethical IMHO. I expect all those 'mint' Leica lenses for sale on FleaBay have had some treatment of this sort. If the etching is bad enough to affect a LF lens, then your grinding might manage to keep the exact curvature of the lens, if you follow the proper pitch lap technique, but changing the thickness of the lens by polishing off a huge amount of glass might affect the lens' performance anyway. Even more so if it's a modern coated lens. I don't mind doing this to polish off a huge number of cleaning marks.