Thank you for the additional details. I will investigate this wallet soon.
You could comment out that line to test what happens. If you do, let me know. Does the wallet work without it?
But this is not a permanent solution because it would affect your other Monero-based wallets. You can’t just copy the code into a new plugin, there would be too many name collisions.
I have to build that wallet, understand what its authentication method is, if any, and then understand why it’s different. As you know, there are several possible authentication methods on HTTP: https://curl.se/libcurl/c/CURLOPT_HTTPAUTH.html
Perhaps it’s a fork from an earlier version of Monero, or it’s simply modified.
Once I have a clear picture of what other authentication methods are possible with these types of wallets, I can add to the coin adapter settings.
I have added this to my backlog. I will get back to you about this, hopefully in the next week.