I set the slider to 8, which gave me questions for C1 and C2, which is where I think my Chinese is at. The tool doesn’t tell you this until you show the results at the end, but if you’re unsure, choose a low number! Below, I show my own reasoning for C2 (I would answer “yes” to all C1 questions, so not terribly interesting).

Listening (C2): “I have no difficulty in understanding any kind of spoken language, whether live or broadcast, even when delivered at fast native speed, provided I have some time to get familiar with the accent.”

Provided that we take “accent” to mean 口音 and not 方言 (and we should), I can do these things. My main problem with listening is that I haven’t spoken with enough people with heavy accents, which is a hurdle when speaking with people from areas I’m not familiar with, but there’s room for this in the description above. I hesitated before answering “yes” here, because it does also matter what kind of content there is. I can listen to a lecture in linguistics without problems, but if I’m thrown into a rapid news broadcast with audio only and little context, it might be hard before I figure out what it’s about. Maybe answer “yes” here is an overestimation of my ability, but it’s hard to say without actually testing it.

Reading (C2): “I can read with ease virtually all forms of the written language, including abstract, structurally or linguistically complex texts such as manuals, specialised articles and literary works.”

While I can read the texts mentioned above, it’s a stretch to say that I can do it “with ease”. I haven’t read enough books to do that, maybe a hundred or so in total. I have to answer “no” to this question.

Spoken interaction (C2): “I can take part effortlessly in any conversation or discussion and have a good familiarity with idiomatic expressions and colloquialisms. I can express myself fluently and convey finer shades of meaning precisely. If I do have a problem I can backtrack and restructure around the difficulty so smoothly that other people are hardly aware of it.”

I have been through grad school in Chinese and teach courses in Chinese, for Chinese teachers. I need to backtrack and restructure sometimes, but can usually do so without trouble. I still make occasional mistakes, of course.

Spoken production (C2): “I can present a clear, smoothly flowing description or argument in a style appropriate to the context and with an effective logical structure which helps the recipient to notice and remember significant points.”

Yes, I feel I can do all this and have done so many times.

Writing (C2): “I can write clear, smoothly flowing text in an appropriate style. I can write complex letters, reports or articles which present a case with an effective logical structure which helps the recipient to notice and remember significant points. I can write summaries and reviews of professional or literary works.”

This is harder. I can certainly write clear, flowing text in an appropriate style, but “smoothly flowing” seems like a stretch. The rest of the requirements for C2 are okay, I think, although “complex letters” is a bit specific to Chinese. I have not even tried to master officialese (公文) and have no interest in learning how to write formal letters properly. With this in mind, I answer “no” here and put my writing at C1.