As I commented in the AUR comments[1] I was not aware of the existence of a ttf-topaz package since I did not search by topaz but by topaz-unicode which is actually the name of the font in the upstream[2] and since I saw that it did not exist I created the package.
From my point of view the one that should be removed is the ttf-topaz[3] as it does not correspond to the real name of the upstream.
In any case I have offered to be co-maintainer of this package to vcalv[4] which I think is the best thing to do.