The short answer is no, I’m not aware of any standard or “correct” way to enter such details. I think that simply being consistent in your own data is the real key. It’s the sort of thing that FAQs are really useful for, for your own memory as well as any members of your site.
In the case of your example I would (being a grammar pedant) just comment that “Convict” is not an event. ‘Conviction’, or ‘Imprisonment’ would be the right words for an event. I might use Conviction for a single-date event (the date judgement was passed?) and Imprisonment if I knew the FROM and TO dates – but checking my own data I seem to have been inconsistent in that regard 🙁
What is slightly confusing when entering this data, caused by the GEDCOM spec not kiwitrees, is that the event descriptor “Imprisonment” needs to go in the second field: TYPE, not in the first (EVENT) field. The latter I usually leave empty. This results in an output like this:
