Hi Peanutsgang, the labels are all from JMdict. See here for an overview over the keywords: http://www.edrdg.org/jmdictdb/cgi-bin/edhelp.py?svc=jmdict&sid=#kwabbr There you can see that "yoji" is indeed the label for yojijukugo. If you find entries that are mislabeled or lack a label it should have, you can edit it in JMdict, and after it is accepted, the updated entry will find its way onto Jisho.org eventually.
However, Jisho.org also sometimes has entries with no equivalent in JMdict (like for example https://jisho.org/search/琵琶湖線 ). These cannot have any labels, as long as there's no matching JMdict entry. For your example however, there is an entry, and you can edit it right here: http://www.edrdg.org/jmdictdb/cgi-bin/edform.py?svc=jmdict&sid=&q=1697720&a=2
Sorry for my late reply, your info was really helpful, thanks a lot @jakobd2
Unmarked yojijukugo
I have found not just this one but a lot of inconsistencies in the labels of the yojijukugo compound (#yoji). Some of the labeled #yoji aren’t really 4 letters compounds, and some real #yoji, like this one, are unmarked.
Who decide, or how the labels for the #yoji works?
I have found this inconsistency thanks to this page: https://yoji.jitenon.jp/