Syncs and dumps fine. You do need to specify -g gl like any other Ruffle game, because libTAS doesn't support Vulkan.
Also make sure Ruffle doesn't open maximized because this game uses a mouse on the main menu and mismatched screen sizes causes a desync. (I'm probably the only one with this problem because I use a tiling window manager...)
Regarding optimization, I did find this TAS from last year made by the same people, which is faster. I'm assuming this comes down to using version 2.5 of the game while this submission uses version 3.0, and the submission says that version 2.5 can't be used in Ruffle? I did find this Ruffle issue (first castle level results in softlock on 2.5), which is quite unfortunate. I think it's fine to accept while knowing it will be obsoleted later if/when Ruffle supports 2.5 and a new TAS is made on that version.
Yeah, unfortunately we can't TAS v2.5 since it softlocks on the Bowser fights. Also, it turns out that the old 4:38 TAS is technically invalid (corner boosting to regain clip speed is actually impossible on v2.5, this is a side effect of how the TAS tool was made), so a v2.5 TAS likely wouldn't save the full 10 seconds over v3.0.