Best bet to get information about CoreGui content is to use Roblox Studio and Play Test.
- Open Studio
- File > Settings > Studio tab
- Look for subsection ‘Explorer’
- Show Core GUI in Explorer while Playing
- Close > Restart if you prefer to
- Play Test
Then you can get all the information about CoreGui that you’ll need to position things you want.
There is no way of indexing, viewing, or getting the values of anything that is inside CoreGui using a normal script or localscript as Roblox intends it to be protected. Malicious users could get the value of the ‘report game’ page’s frame position and kick/crash the user before they could even hit submit.
If you intend to attach something, best bet is to disable it from SetCoreGuiEnabled and fork your own version.