No one can be sure what information they can gather from your pc. The Jagex software have access to your basic system information, os, languange, ip and so on and might also see running processess.
I analyzed the installation file with Hybrid analysis. Someone with more knowledge can explain what these results can tell about osrs software capabilities on information gathering. Here is the link: https://www.hybrid-analysis.com/sample/5175174061ac2e1b4e7078d564b9dda553853938f4179412bf9d18840e33fc70/64da87f33827d7e5de03bd98
