Oh dear, the answer is very complicated - but you're only forced to ask
because I oversimplified to begin with so I'll try my best to keep this
short.
As far as Roman Catholicism is concerned, there was a constant pressure
placed on Bosnia to adopt strict Roman Catholicism (the Bosnian Church
was a heretical Roman Catholic sect that grew out of the Roman Catholic
Church's weak hold on this region). Even devout members of the Bosnian
Church, like King Kulin, renounced the Bosnian faith to please first
and foremost Hungary but also Rome. From that point on, all Bosnian
rulers claimed to be Roman Catholic for military, political gain but
there is absolutely no evidence to suggest they adhered to this; and
the population as a whole certainly remained loyal to the Bosnian
Church. King Ostoja Kotromanic was the first to again publicly declare
himself a member of the Bosnian Church, centuries after King Kulin
renounced it. So there was always this duality present.
Despite this, there were several instances when Rome openly ordered the
extermination of the "Good Bosnians" (Dobri Bosnjani). There were also
near constant incursions by Roman Catholic forces from the Balkans. I
remember reading at the national museum the most probable death toll
and it was tens of thousands spead over several centuries, which is
quite high given Bosnia's medieval population. On the other hand,
Franciscan monks made their way to Bosnia at the same time that the
Bosnian Church was taking root and by all accounts established
themselves as a force for good appreciated and admired by all people in
the kingdom. Even today they're still called "Uncles".
When it comes to Eastern Orthodoxy, there was a steady series of
territorial wars with Serbia during this era that most certainly had
religious undertones - as did the 1992-1995 war. While the main
conflict was always between Eastern Orthodoxy and Roman Catholicism,
the Bosnian Church was trapped in the middle then as Islam in Bosnia is
today. So it is not completely accurate to classify these wars as
religious, any more than the 1992-1995 war was. However, they did
contain elements of forced conversion and/or extermination as part of
overall territorial conquest package. It was not as dramatic as the
conflict with Roman Catholicism because Eastern Orthodoxy had no
presence in Bosnia and Herzegovina during the formative years of the
Bosnian Church. Bosnia's first Orthodox churches are built on territory
that belonged to medieval Serbia when they were constructed and it was
only through conquering these areas that Eastern Orthodoxy became a
part of Bosnia and Herzegovina.
It was at this point that the Ottoman Empire conquered the region and
the Bosnian Church collapsed due to the enormous losses of members via
conversion to Islam. Islam, obviously, became dominant so neither Roman
Catholicism nor Eastern Orthodoxy were able to establish (or
re-establish in the case of Roman Catholicism) authority in Bosnia and
Herzegovina. It's also unclear what might have happened had the Ottoman
Empire not arrived. When King Tvrtko Kotromanic of Bosnia conquered
Serbia and much of Croatia, the Bosnian Church was no longer the
dominant religion. All of Bosnia's rulers claimed to be Roman Catholic
and put on a bit of a public show to assure Europe's continued
patronage, and now with a large Roman Catholic population - that could
have been expected to be much more sincere. The largest religion by
population would have been Eastern Orthodoxy and with free movement of
Serbs into Bosnia and the regions of Croatia held by the Kotromanic
dynasty, that could have had a significant impact.
But we'll never know (Thank God).