Theoretically you are right but I read reports of KP Immigration to have set the next 90 day reporting date on the paper stapled into the passport as the same as the "admitted until" date of the extension which then comes to 60 days instead of 90.
I noticed that this message appears when trying the online reporting outside of the correct date window.
I am not sure if it's still 15 days to 7 days before the reporting is due, I slightly remember having read recently that it has changed. The experts in this group will know and hopefully tell.
well, no paranoia so far but it might come up if there are indeed known cases of denied re-entries with proper permits... I know well that normally re-entry is no problem in such cases but we all know that things don't always work the normal way in Thailand 😉