I am a novice in www/lynx so I only know the basics.
When I click the Post thread button it shows an error message like Oops we run into some trouble.
I created an account in the XenForo community forums and I created the following thread https://xenforo.com/community/threads/lynx-be-able-to-post-messages.151907/. As you can see the moderator told me that in order to have support I had to pay a license
P.S. The XenForo thread was created in the Public forums >> XenForo suggestions but the moderator moved to Closed suggestions and <snip> was the link of this FreeBSD forums thread so I suppose that the moderator removed it.
I very rarely test things with lynx, but the screenshots at <https://xenforo.com/community/posts/1553014> might help the developers of XenForo to (broadly) pay greater attention to accessibility as a sideline to (narrowly) fixing a confirmed bug that affects profile posts.