Surely the next step is to tweak the open source font with AI to slightly better target the desired font?
Sometimes you're trying to replicate a logo and they've hand tweaked a letter or two, or stretched it.
edit: (Google Fonts actually have fonts you can natively stretch and some with replacement character variants) I wonder if the tool uses that to better match?)
Sometimes you just don't want to pay for a fancy font and I believe font shapes are not copyrightable?