Hello ,
Thank you for posting in the community your question about these effects and recommend you also ask in the facebook community as more users are actively looking at posts there and will get more feedback. https://www.facebook.com/groups/twinmotion.community/
You can also make a suggestion on our road-map for improved caustics:
https://portal.productboard.com/7pu88c9kpmqtzt8hwg6arujh/tabs/4-under-consideration
Kind regards,
Vincent B.