So, the answer is to let go of what things look like, and concentrate on what things mean. q and cite are not about emphasis, they are ways to say "this sequence of words is a reference from or to another work". That could be a title of a book, or a line from a song, or a quote from a speech, or a number of other quotes or cites.

In some cases it is a judgment call, and don't get too tangled up in it. There's a reference page called Paragraphs, Lines, and Phrases, that you may find useful to check your decisions against.

In general it seems to me that you are focusing on what things look like - italicisation - but this way of communicating by manipulating typography, is purely sighted. It's not relevant to (most) users of screenreaders, just as it would not be meaningful in a radio play or a phone conversation. But these ways of conveying narratives are semantically rich, aye? So instead of thinking 'how can I make it look this way?', think 'what am I saying when I make it look like this?'.

If you can work out what you really mean, it is much easier to decide how to say it. This is as true with coding as anything else.