I mean, standalone recordings don’t have their own section on the artist’s page “\https://listenbrainz.org/artist/[id]”. They don’t have any release group or something like that, and maybe because of that they never appear on these pages. I’m not sure.
See, for instance, “Swimming Cat”, “Алюминиевый дождь”, “Minachu”. They have only video recordings I added on MB and nothing apppers on their associated LB’s pages (Swimming Cat, Алюминиевый дождь, Minachu).
On a side note, your cover recordings may actually be a release. Standalone recordings are mostly music videos of other recordings or recordings that is waiting to be released in a full album. YT only recordings can count as releases too!
If so, I think that the problem is really they are not releases. Then it means I misunderstand the concept of “standalone recordings” and “singles”. What is the difference between them and how do I know which one I should use? I read discussion about it and didn’t understand what is a final decision. Most covers on YT, which is my main platform for listening to them, are maximum can be added as singles and not as a part of full album. And they often don’t have any version and won’t have on other streaming platforms, where it is much easier (at least for Spotify, because every track can be added as a single). @chaban also has explained to me that video recordings are always must be added as separate recordings.