Many thanks Wanja, Eduardo, Stefan, Adrian and everyone else who has contacted me recently offering to help with QA testing.
According to the Moodle 3.8 QA testing dashboard we're now up to 68% (400) tests passed and 7 failed, so more testers are certainly welcome!
The forum tests previously on hold (awaiting related issues being integrated) are now open, including some labelled 'new', which cover improvements and new features in Moodle 3.8.