As a native German speaker who also knows English (obviously), I'd rate the comprehensibility of the others as follows:
Swedish: understood just a few words
Dutch: understood some entire phrases
Yiddish: understood entire sentences, but there were still some words I couldn't recognize, which I guess might stem from Hebrew or Slavic languages. (But I did know about some of the more regular sound changes relative to German before, like Augen → Äugen.)
Importantly, there is a difference between comprehension and production. Just because you can mostly understand a language, doesn't mean that it isn't a language in its own right. Yiddish, as an example, has many syntactic differences from German, in addition to its differing vocabulary.
Scots is absolutely a different language from English, despite it being intelligible. I can't produce that speech, even with an accent. It has different rules and formations that My English just doesn't have.
Yes, it's true. There are unique words in Ladino that a Spanish speaker won't be able to identify, but my main takeaway is that modern Spanish and Ladino are mutually intelligible.
As a native German speaker who also knows English (obviously), I'd rate the comprehensibility of the others as follows:
Swedish: understood just a few words
Dutch: understood some entire phrases
Yiddish: understood entire sentences, but there were still some words I couldn't recognize, which I guess might stem from Hebrew or Slavic languages. (But I did know about some of the more regular sound changes relative to German before, like Augen → Äugen.)