As anyone who translates knows, some words and phrases just plain don't have a "proper" meaning in other languages. There can be ambiguity as to the exact term to use, and information is very often lost in translation. I think attempting to use common English terms in an attempt to cater to the English-speaking audience does a disservice to communication, and thus to effective Q&A.
I shall present a related anecdote, which happened to me in real life:
One day I got into an argument with a friend of mine after he told me that he intended to go to the grave of a recently-deceased relative and pray. The debate was rather heated, and we were throwing (vaguely remembered) hadiths at each other to support our respective positions. The situation was no closer to resolution until he clarified that he had meant pray in the sense of "say a du'a", rather than pray in the sense of "perform salat", upon which the rulings are very very different.
I believe that the use of common "jargon" is fine, even with no attempts to simplify it for the layman. It effectively acts as it's own filter; if the reader doesn't know what the question is even asking, they are probably not qualified to answer the question. So long as the jargon is common knowledge to the expert-tier of answerer that the questioner is targeting, then it's fine.
Answers should cater to the level of the question; don't throw around terms like al-walaa' wal-baraa' (at least not without explanation) unless it's reasonable to assume the questioner would understand it. So if a question is obviously asked from an outside or beginner perspective, a good answer would take more time to explain complex terms, and translate everything into simpler English.
That said, if there is a complex term that a newcomer doesn't understand, just posting a separate question along the lines of "What is al-walaa' wal-baraa' and why is it important?" should be on-topic (assuming it's not too "general reference").