I'm a newbie and I haven't found an answer to this in a cursory search.
I installed the Unicode Fonts Hack that lets you read cyrillic. I used the Droid one. Now I'm wondering if I can safely overwrite that (without going back) using the darkened font from this site
https://sites.google.com/a/etccreations.com/kdesignworks/Home/font-install-files

I would still like to read cyrillic but darker

Thank you for your help (anticipated)

ah - unfortunately the fonts I've got (except for my modified version of Droid) are not full unicode character sets.
But you're welcome to try the modified droid.
As for your question, just install another font, no need to uninstall.