FWIW titanium especially in thin sections such as bicycles is not hard to drill, especially if you are just enlarging
an existing hole. Fresh drill a good idea. Can't comment on size as too little
info as to location but some kind of grommet is needed for any hole in metal through which a conductor is passed.
Drilling a new hole in a curved surface (ie bottom bracket) requires some care with center punching and starting
with a smaller drill such as 2-3mm and then the final size drill. Work hardening can occur so a bit of lube and
slower speed is a good idea.