Migration from SP 5.x (Joomla 3) to 7.x (Joomla 6)

Is it possible to migrate from SP 5.x (Joomla 3) to 7.x (Joomla 6) ?
Both are multilingual
We tried migrating the DB tables, but got stuck with categories and assets being very complicated linking to each other.

I wouldn't even recommend going from Joomla 3 directly to Joomla 6. Better do it step by step using the Joomla updater, I doubt you see the update to Joomla 6 in your Joomla 3.
For Sermonspeaker, the tested upgrade paths are from major to major version, bypassing one could work, but isn't tested.
So better upgrade your Joomla 3 to Joomla 4 (or 5, depending what is offered) and then update Sermonspeaker to version 6 and check that things work, then update to Joomla 6 and upgrade Sermonspeaker to version 7.