Is this resource accurate? (Sindarin grammar)

Like the title implies, I've been looking through many different resources, and I found this site. I have an outline of the information from the site in this google doc, which also includes a few notes and some phrases I'm tinkering with. (Admittedly, I'm very new to this, so the phrases are most likely inaccurate.) I also did some interpretation of definitions to use for the phrases, basically guessing at possible slight differences between words with similar definitions. (Hîr and Brannon, for example)

All was fine and good, but while browsing the forums here, I found a post stating that the linked resource was outdated. If this is the case, could someone link me to a better source?

Thank you!

I will copy the relevant entry of the FAQ of our Discord group:

Where can I study Elvish?
Interest in Tolkienian Linguistics mostly faded after the early 2000s. In the meantime, some of Tolkien's most informative notes and essays (not lessons) on his languages were published. As a consequence of both, most of what one can find on the internet is now outdated; Tolkien's later works either debunked our theories or replaced his own older works. There are currently a few courses which employ these new findings in their lessons, but they are yet to reach their final stage. Thus we recommend practising often in the group, regardless of which source you use for your studies, so that our experts could make corrections on what they offer.

That website is very old, and so (as explained) it is inaccurate, containing more guesswork than attested information (due to the lack of the latter at the time). The linked course is currently the best available. But no course can match the collective knowledge of a community, so I recommend checking in with this forum (for detailed questions/answers) or the Discord group (for quicker questions/answers).