性 as a suffix that usually adds an emphasis to the nature of something, the state of something, or that describes something that is usually in that state or concept. For example, the word "忍耐" means "patience," and by adding 性, we get "忍耐性", which means "the quality of being patient" or "patience."

Ultimately, I believe the original text is stating that it's unclear whether certain elements are in a state of co-presence or not, if they can stay in a state that allows them to be adhered together (and stay that way) on a chemical/physical level or not.

I hope this explanation was helpful!

--------------------------------------------------
Note added at 10 hrs (2023-02-17 12:36:42 GMT)
--------------------------------------------------

Another suggestion would be "state of co-presence", which sounds better to me, but may require a little more freedom to change the formatting in your translation.

I also found a patent link that uses this term here:
https://patents.google.com/patent/US20130309701A1/en