As a quick quality of life improvement, please consider adding support for larger font sizes in the Floating Lyrics window (+ and - UI buttons). Sometimes you want to quickly enlarge the lyric text for it to be visible from farther away across the room, and (unless I missed a setting) the existing zoom options are extremely limited.
I'd also add the standard zooming shortcuts support (CTRL-+/- and CTRL-mousescroll) used by most browsers and text editors for both the Floating Lyrics window and the Lyrics panel. So, when the Floating Lyrics window is in focus, CTRL-NumPlus or CTRL-MiddleMouseButtonUp would temporarily increase its font size, and CTRL-NumMinus or CTRL-MMBDown would decrease it (exactly like the +/- UI buttons). If the regular Lyrics panel is in focus, the shortcuts would do the same there but save the new default size in the settings (since it's more likely that people would want to set up and keep the anchored panel's new size as default, rather than zoom it temporarily.)
Another fairly easy improvement to consider Floating Lyrics is the ability to select select and highlight a line (same as clicking an item on the playlist would highlight the whole row), to make following non-synced lyrics manually easier. Keyboard Up/Down arrows to select previous/next line (when the window is in focus). Can be applied to the Lyrics panel as well.