DISCUSSIONS on “Rules for online games in HoMM3 and formulas for calculating player rating.”

So, I can enter a treasure room or fly over a guard post, and that doesn't contradict point 5.13.

Correct, you can. Point 5.10 removes all restrictions except for point 5.13. That is, you still cannot take anything from under a shifted guard without defeating it. You can move freely around respawn points and treasure rooms. The "flight" and "dimension door" spells also allow you to bypass the guard without defeating it.

Exception 1 - the Jebus template, where you always need to defeat the guard at the respawn point.
Exception 2 - templates with companions, where it is recommended to make an amendment to the rules: you can completely bypass the shifted guard of a passage if it is not a guard post.

It seems that it is not written very clearly, as questions constantly arise. Many beginners, just to be on the safe side, always defeat all guards, including guard posts.

common sense tells me that this means:
It is forbidden to take Pandora's boxes, scrolls, artifacts, or visit various objects from under a shifted guard without defeating the guard of that object FIRST.
but on the other hand, if that's the case, why isn't it written that way?
that is, can I take, say, a Book of Fire, and KILL the GUARD of that book WITH that same book?
Sorry, maybe I don't understand obvious things, but it seems to me that it could be written in a more understandable way...

That's a reasonable point.