I just did a quick search on the surname BACA at FamilySearch.org
It appears to be primarily a Spanish name.
If it transferred to the kingdom of Bohemia long ago it may have
been as far back as the Thirty Years War which was fought by
a lot of international mercenary soldiers.
There was a strong connection between Austria and Spain
because the Habsburg dynasty sat on both thrones.? There was
aso the war of Spanish Succession fought by Austro Hungarian
regiments in Spain.?? Some Austrian regiments were badly
mauled and it is very possible they took in Spanish recruits
who went back to Bohemia with them.
I have a short one-volume history of IR 35 -- the Pilsen Regiment.
It tellss of that war and others way back when that could well
have brought Spanish names to Bohemia.?? Italian, Irish and
other surnames also ended up in Bohemia as a result of wars,
mining, and other trades.