Dear John,

I am a user of the elog system and no developer, so no complete answer guaranteed.

The quote of the manual describes the case, if e.g. an hardware component discovers a failure and the connected PC makes an automatic (new) entry to the elog. Probably modifying an existing one.

I have small concerns on your solution. The description of your alarm system sounds the other ways around, as you are doing something, depending on the elog entries. Based on your statement on JS and dedicated start page, you want to do it on client-side and not on the server. Where I can see the issue, if there is not client, then there is no alarm. As you want to change the date of the entries, I believe, you want to reuse the same entries multiple (infinite?) times instead of creating new ones. The later would be the style of an logging software like elog.

As far as I know, the Date attribute is special and cannot be changed by submitting something to the elog server. as this would make "Restrict edit time" useless. You can try it with this in your config:
Subst on edit Date = $date
Making an entry and edit it afterwards. The entry time stays the same.
If you really want to use this attribute, you have to do some scripting to the actual saved .log files, but this is not intended as I believe.

What you can do, is using an alternative attribute like "MDate" with the config:
Subst MDate = $date
Subst on edit MDate = $date
This will update every time you edit the entry.
Then you probably want to add something like this to your config
List display = ID, MDate, Author, ...

Or "Update" using the duplicate function on the old entry, where you want to change the date, creating a new one with the same content.
Or "Update" using the reply function to create a new entry, referring to the old one.

I hope, I could help.
Best wishes,
Sebastian