Fairly sure it has to do with how voice lines are stored in memory. It is very resource intensive to store and que them since every second the RAM asks- is it done? Is it done? Is it done? Ok play this. 8 lines of speech that are most likely done by sound vVA need to be rendered and processed into the right format and then processed in real time to the right speakers.
This is why Larian have set it to 4 companions and not 8 like the mod. Maybe with enough hardware it would be possible. That or maybe your mod bricked something. I don’t run any mods and my companions say more then one line.
The above interruption problem can be seen with monologuing by NPCs. If you steal or attract them, they stop and never continue speaking. This is something larian needs to fix or change
Am I in the BG1 forum? It can be an issue if you have 4 MB ram.
Voice lines resource intensive? Yea, WTF ROFL.
If BG3 tried to be even be close to BG2 by modern standards (with 20+ playable NPCs- versus 7, party of 6 - versus 4, day/night/time based questing- versus NONE, bazillion dialogue options with banters - versus cinematic shit show, tons of classes/kits - versus the bare MINIMUM, 300+ spells, strongholds, RtWp, etc...)
we would have CPU meltdowns, RAM implosions, and Larian staff would lose their minds.
So ill settle with what we have now with DOS2.75

Oh sorry I mean Baldurs gate 3. Fun game. Forgettable gameplay. Hardly legendary status like its predecessors (Oh yea, sorry. THEY ARE SOOOO OVERRATED lol. whatever zoomers.) Will probably sell great thanks to the one night stand romance part; and the pretty face editor. We now only need a bit more hardcore stuff to make it a hit.