For those who don't know (like us 30 minutes ago), all video games are required to obtain official approval before public release in mainland China. Publishers in Guangdong province (like Wahlap Tech for the mainland-China Taiko no Tatsujin) will have to do this via the industry authority of Guangdong Entertainment & Game Industry Association (GEGIA). Submissions and approvals are periodically updated to a public database on the association's website.
Found via the Year 2025 Third Batch list of video game titles pending approval, it was discovered that Wahlap Tech has submitted a "Taiko no Tatsujin Autumn 2025" (No. 77 in the screenshot) through this pipeline. While we have no concrete info on the actual release at this moment, we should be able to expect further announcement from the publisher when the time comes.
Thanks to 田七不甜 from the Taiko no Tatsujin Discord for alerting us of this database and info about the new version!