I wonder what criteria you apply to determine the trustworthiness of a project. For me, signing a CLA or otherwise not using inbound=outbound licensing is a major one, as well as any project backed by a company with VC funding. Any project backed by a single organisation instead of a group of people from lots of different organisations is a red flag, with some exceptions for long-term known-trustworthy non-profits.
None of that helps with a situation like Audacity/MuseCore though, if developers are willing to sell out their project copyrights, that isn't something that you can really protect against, except maybe discussing people's opinions on that openly.
The other issue with withholding changes from upstream is the potentially infinite cost of updating your changes as the project evolves, things like git-imerge, mergify or git-mergify-rebase can reduce that burden by letting you do incremental rebases/merges though. Normally I don't contribute to projects with a CLA assigning extra rights to corporations over the license, but I've been considering signing one just to drop the maintenance burden.
https://github.com/mhagger/git-imerge
https://github.com/brooksdavis/mergify
https://github.com/CTSRD-CHERI/git-mergify-rebase