yeah that is one of the most disappointing “features” of TestRail.
It seems they do not understand the impact of not having such public list. Features, people ask for years only get a “we added a vote”, but no information what-so-ever about any plans on them. This is frustrating and leads to lack of trust in my eyes.
I do not understand the fear of overpromise or similar. It is a sole thing of communication to not promise too much.
If you look a the “sister-company” Ranorex - they have an open roadmap (https://www.ranorex.com/product-roadmap/), that gives a nice overview and with https://www.ranorex.com/uservoice/ they have a community discussion with active feedback.
But I doubt TestRail will change this - it has been like this for years and with the hickups of the buying and the resulting irregular release-cycling, not their strongest part.
BUT - the communication on the forum has increased massively and this is a good starting point. This is really nice to see that they improve on that area