Yes, standardizing everything to TheTVDB naming and numbering will do the trick:
viewtopic.php?t=2769

Plex will expect you to name your files like so:
https://thetvdb.com/series/re-zero-star ... official/2

If Plex still doesn't show nice metadata despite correctly naming files, then there's probably something else going on as well
(e.g. caching would be the usual suspect), best to check with the experts on the Plex Forums for these kinda issues:
https://forums.plex.tv/