you for reaching out on the community and telling us about your issue. I do apologize for the issue you're having. I was taking a look and didn't notice any unusual errors when trying fake credentials. One thing we can try here is in a test file that we're able to try connecting in a test file. I'll leave steps down below.
Don't use any of these characters: * ? < > | " : \ / (asterisk, question mark, left and right-angle bracket, pipe, straight quotation marks, colon, BACKSLASH, FORWARD SLASH). Also, don't add the .qdf extension; Quicken does that for you.
After adding accounts, see if you are experiencing the same problems in this test file. Depending what we're able to find out we'll see what our next best step is.
Thanks for the update. Generally with 297 errors there's not much we can do on Quickens side as the error is related to the FI's server as it's a direct connect issue and we do not have access to the FI's server. In this case I would recommend contacting UESP so that they're able to take a look at exactly what's happening. I believe you've already done the support steps for the article for the 297 error so unfortunately we don't have much more to do. I do apologize for any inconvenience this has caused.