Thanks. I will report back.

This "international flights" only rule also applies, for example, to some Polish airports and there obviously is aimed at keeping domestic travellers out of the lounge per se. So I was not sure if the same applied to Croatia or if it indeed is simply the result of the temrinal layout, as you suggest.

Croatia has entered the Schengen area on January 1, 2023, so there must have been changes to the terminal layout as now only a relatively small number of flights will require immigration - unlike in the past where all but the domestic ones required passport control.