Coming to this late. But I’m running two variants of this kind of solution, and want to add to the discussion in case it’s helpful:
One variant is kookma’s refnotes solution, which takes pasted bibtex json data, using a custom dropzone (or “paste zone” in practice for me), which you can find here: Refnotes 1.9.0 — references, citations, footnotes and abbreviations in Tiddlywiki … and transforms in various ways to translate into the TiddlyWiki field-structure that refnotes uses (prefixing most fields with bibtex- etc.).
The other takes jsons exported by my university’s (= your alma mater’s 
) moodle LMS, and makes various transformations on these (since the json I can export from moodle doesn’t even come with a title field, for example), so they can be imported. See discussion thread with key post here: