It's possibly the GOG download. Someone I know encountered that issue, he looked into it and it seems to only happen with the GOG version.
Indeed I use a GOG version, it already was my suspicion that this is the cause of the problems! I will be installing NWN again but without GOG and I'll reply back here if that fixed the door bugs for me
I somehow got inside the temple, by pressing W at the door -- but couldn't see any clickable doors inside, no way I want to play like that
gotta fix it!
Edit: Thank you ALL for fast help and response
I didn't expect that! Finally I have hope to solve this issue.