No, it can't be used with Revamped, because it breaks singleplayer saves. "You can't play this mission, it is dependent on content that is missing: namalsk_a2"
Ambient birds namalsk does not do this.

@Disco, according to weyn666, who uploaded the revamped version of Namalsk, this version of Sullen Skies for Namalsk works for the revamped version, although after checking it does throw an error upon loading (which can be ignored) and seems to work just fine.

would you be able to make it work with Namalsk Revamped? https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3013966707

Thank you