Unfortunatley for me, I have gone through every shortcut and could not find one that duplicated the Increase Point Size by 5. The odd thing is, even if I reassign the Increase Point Size by 5 to something else I keep getting that character.
Update: I finally had a font in which the character appeared. Turns out I'm getting the glyph for the Latin Capital Eth/GID1/ unicode 00D0. From more research, it doesn't even look like its possible to assign a shortcut to a specific glyph! I may have used that glyph ONCE (it looks familiar) but I certainly didn't create a shortcut.
Did you ever reset the prefs as I advised back in September?