I think Nextcloud Talk is a good software. Unfortunately, the installation and configuration is not easy. Do you use the High-Performance Back-end (HPB)? Maybe you need only a Nextcloud Talk hoster e.g. https://www.spreed.eu (Struktur AG).
Would you mind elaborating on which bugs you encountered when trying out Collectives? Also, which features do you miss the most there? I’m curious to learn what can be improved