miamicuse writes:

Should I chip them out and replace
with real grout or is it "OK" what I did?

Both are essentially portland cement plus sand. Thinset is hidden so it
can employ the cheapest grey portland cement. White or colored grout uses
white portland cement (more expensive than grey) so that it is either
white, or can be tinted. Since grout is non-structural just about any
cementitious base would suffice, unless you are looking for decreased water
permeability.

The ancient craft used the same stuff for setting and grouting.