Just my experience with pretty chrome bolts......they have always leaked for me. On my water pump the lower bolts on the right and left (in your picture) will need a little RTV on the threads (if I recall correctly). Possibly the ones on the under side of the pump (not in the pic)....can't remember.
FWIW, I use strait water when I fill my radiator after a rebuild, just in case there is a leak. It is much easier to clean up, and it is easy to drain out and add coolant after you have leak checked everything.