Serato writes the cue and grid point info to file. Traktor writes it to the collection. Rekordbox writes it to the collection.
Prior to moving over to the Denon Ecosystem, I used Serato as my master database and synced that database to Rekordbox and Traktor using Rekordbuddy in an OSX VM.
Where does Serato write the info? Does it write it to a custom ID3 tag? Traktor 3 has an option to write to file - so as long as they both write to separate ID3 tags we should be golden…
There are also third party tools available to make managing this easier. For example, if you set a bunch of cue points in Serato, why also duplicate that work in Traktor? Or Rekordbox?