Anyone got a month or two to spare? Seriously though - since we are all agreed that <code> markup should encompass whole commands, the logical first step is to correct such things as we find them. Even if we felt it worth the time involved, there is no way that you could search for and find such broken instances, so it's down to alertness and common sense.
To be honest, I would rather not include new tags such as <kbd> unless we can see a genuine advantage to it.
One more point. Generally we use wiki-markup (with a few additions thrown into the mix) but as a rule we discourage use of HTML markup as it tends to interfere with wiki-markup in unpredictable ways. For this reason I would prefer not to introduce more HTML markup in the guidelines. Better a new template, if it is really needed.