Hi there - Lindsey here from Support. I hope you're doing well notwithstanding this issue!
I'd be happy to help. :-) It looks like the main error you're seeing is in regard to 'Alternate page with proper canonical tag', correct?
If this is the primary issue, all this means in Google Search Console is that there are two versions of a page on your website having the same canonical URL. Google will simply exclude the duplicate version and index the main version of the page. I've found a great resource here that may help provide further context: https://rankmath.com/kb/alternate-page-with-proper-canonical-tag/
To help with this, there are a few things that can be done:
It's possible that Google seems to have found more than one link pointing to a page with a canonical URL. A few possible cases are (1) There are actually several pages with the same canonical link or (2) there's a trailing slash (/) in both urls (which I believe I'm seeing a few instances of).
For further context, it's possible that two URLs point to the exact same page. Google then chooses to index one and drops the other one (leading to the index error we're seeing). One way for Google to know it’s the same would be to implement a page redirect from URL A to URL B so Google would know for sure they are the same. To fix this, you'll need to review the urls mentioned and ensure that the proper canonical tag is used/detected for that page. You may need to review you sitemap for this in case there have been any recent changes.
If you need any help with this or are unsure what to do, I'd be happy to relay this to our extended team for this to take a closer look and find exactly what you need to change and how. :-)
Otherwise, you can also share read or restricted access to us in your Google Search Console with firstname.lastname@example.org and I'd be happy to take a closer look at any errors you may be seeing.