When I try to export the collection using Better BibLaTex, I get a lot of non-standard @online entries that are in fact incorrect. Is there any way to update some fields so that they become @article instead?
But how is it saved in your Zotero library? When you select the item, does it say Journal Article or Webpage for the item type at the top of the item information pane?
I imported it by clicking on Cite and select EndNote. It says "Journal Article"
I think I found the problem. I was exporting as Better BibLaTex instead of Better BibTex. Using Better BibTex seems to have fixed the issue. But it is still weird that Better BibLaTex would explore 90\% of my articles as @article and the rest as @online.
This is expected for Better BibLaTeX exports of arXiv preprints. The BibLaTeX documentation lists 'journaltitle' as a required field for the 'article' entry type. Related to this, the Better BibLaTeX translator recently changed its default export of arXiv preprints from 'article' to 'online', which seems to be favored by BibLaTeX developers. You can customize the exported entry type with a BBT postscript.
Unlike BibLaTeX styles, BibTeX styles can't be expected to handle eprint information properly. Therefore, Better BibTeX is exporting arXiv preprints as 'article', with the arXiv information in the 'journal' field. If you prefer 'misc', use this postscript.
Upgrade Storage
For example, you can import from the below and export with BBT to reproduce.
https://scholar.google.com/scholar?q=info:4w4edGgXF20J:scholar.google.com/&oi=gsb&lookup=0&hl=en
I think I found the problem. I was exporting as Better BibLaTex instead of Better BibTex. Using Better BibTex seems to have fixed the issue. But it is still weird that Better BibLaTex would explore 90\% of my articles as @article and the rest as @online.
Unlike BibLaTeX styles, BibTeX styles can't be expected to handle eprint information properly. Therefore, Better BibTeX is exporting arXiv preprints as 'article', with the arXiv information in the 'journal' field. If you prefer 'misc', use this postscript.
See this discussion for more details:
https://forums.zotero.org/discussion/85274/zotero-needs-a-preprint-category