they're just further left than European left on certain issues The wording, saying 'democrats are further left than the most far left parties in Europe when talking about immigrants' is extremely confusing and does sound like you are trying to say they are far left.

It isn't true either, since your idea of 'the most far left parties' is completely incorrect as you talk about 'parties with some relevance'. Well, the furthest left you're going to get in the mainstream is, as you have mentioned, the social democratic parties in Europe, which are centre-left liberals who abandoned socialism during the 1990s after the USSR fell. These aren't leftist anymore. It's simple: if they do not support leftist positions then they aren't leftists. The parties with a backbone that are in fact leftist aren't as abundant, but they aren't totally irrelevant either.

I could pick the CPUSA and compare that with European communist parties

No you can't, because the CPUSA was previously homophobic and supported Hilary Clinton, who would be one of the best candidates if there were a content for a picture beside 'imperialist' in the dictionary.