It would help that a programmer has a look at the parameters interface with large fonts (I have to use a minimum size of 22). My Windows parameters are 225% for the characters enlargement, 125% for the windows enlargement. This currently resides in the ergonomics section of the Windows parameters in Windows 10.
I shall just take an example, perhaps it is not the best one :

I saw somewhere that for the screen copies somebody advised to launch Free Commander with the options /NewIni=FreeCommanderTest.ini /NoPlugins /Lng=English
It is not really a very good idea, as FreeCommanderTest.ini resides in the executable path, so this results in a rights refusal message, even for a Windows admin. I imagine it would work after requiring an elevation of privileges, but that is perhaps much for a screen copy.
Anyway, this would not exhibit problems linked to the fonts sizes.
Concerning the question of the tooltips that appear in white on (nearly) white background, for several colour themes, I saw that a solution was found for the donor version. Can we imagine that this will appear on the public version in a near future ?