Hi. Well, any field that is set to 'hidden by role' or 'hidden to anonymous users' never actually gets rendered at all (if they are not in that role) and therefore it will only update the core when its registered. I will have to check on the read only field. Since it won't be changed at all it shouldn't ever change and therefore not change the CORE right? Also, I think whichever field is 'last' is actually the one that its going to look at. So if you have a question that admins can see called that is 'hidden' from other users, but under it you have the read only field... and they are both linked to the core property value, then it doesn't matter what the admin sets because the read only field has a greater sort order. You might try switching the sort order of these two fields.
Ok... that just gave me a headache
-Chad