What does the term "delicate genius" refer to?
I don't think the Seinfeld definition really amounts to any more than an opportunity for 'larky' humour.
In common understanding, a delicate genius would be much the same thing as a volatile or unpredictable genius. True genius is obviously quite rare, and most of us don't really understand it.
But it is common knowledge that genius/very high intelligence has a tendency to correlate with mental instability (e.g. van Gogh), and poor social skills (e.g. Newton)
In general I'd call someone a delicate genius if I wanted to highlight the idea of he/her needing to be handled carefully in order to get the best out of their special abilities. I'd call them an unpredictable genius if I wanted to indicate that even with careful handling you still might not get the result you want.
In either case, OP could consider it a (slightly back-handed) compliment. The implication is that OP is normally expected to do exceptionally well, and any lapse from that high standard must be down to the nature of genius, not his stupidity. But in context, it was probably a bit tichy (tongue-in-cheek).
I have not heard of any official definitions of the word and I doubt whether whoever referred to as delicate genius had the Seinfeld definition in mind.
I can think of one explanation given the context.
- Someone who is often brilliant, but occasionally makes a mistake. Like you would be a genius, but for the (occasional) mistakes. (An almost genius, if you may)
If I had to guess, I would say that the person who made the comment heard that from somebody else who heard it on Seinfeld. Having no idea about the Seinfeld context, the person made their own assumption on the meaning and finally you became a delicate genius.
Note: All this is a mere conjecture on my part and I would like to be corrected, if I am wrong.