No worries, I have plenty of moments like that myself!
The numbers after the Image ID aren't dates though; they're just sequence numbers. If they happen to correspond to days of the month in your case, that's just a coincidence.
In terms of attaching a log file, there isn't a great way to do that because the log itself is an HTML file, but you'd want to remove your license key that appears at the bottom. So I usually recommend just selecting the desired text and copy/pasting it into a post. For something like that, putting it into a "code block" would be desirable. To do that, mouse over the Insert button under the box where you write a post and then click the "</>" icon. That will open a code window. Paste your log into there, don't worry about the code language option, and click Add Code. You'll end up with something like this:
This is a code block.
It uses a fixed width font and disables auto-formatting. For example, typing :) outside of a code block
would cause those characters to be replaced with a smiley face, but not in here.
It also disables automatic line wrapping.
And it's just a handy visual cue to separate someone's post from their log.
If you had an extraordinarily long log from some other area of Reflect (i.e. not a backup job log), an alternative would be to paste the contents into a text file and simply attach that file to a post.