Other than very common scenarios like introductions, spare yourself the headache.
If you are a diplomat or something similar, understanding it might be useful, but using it can be a minefield (e.g., you better know the hierarchy of everyone around you so that you use the appropriate language).
> I would love a tool to help put me in positions where I need to use keigo
In most if not all cases, if you find yourself in a situation that keigo is both standard and expected, one of two things will likely be true:
1. You will have been selected based on your ability to use keigo (e.g., customer facing roles that use keigo like banks).
2. There will be one or more people in your organization who will make sure you know what you need to know.
Most non-native speakers I have known who try to learn keigo use it in really unnatural and sometimes awkward ways.
I have known three people who “got it right”, and maybe a fourth. All are super fluent in “normal” Japanese and are lifelong students of the language.
1. Currently a professor of Japanese. PhD in Japanese from U Hawaii.
2. Polymath Cambridge grad who worked for Cambridge University Press. It was not uncommon for Japanese people to whisper to me about how freakishly good his Japanese was, especially when speaking about formal or technical topics.
3. Power nerd who went deep into the Japanese sword drawing martial art (iaidou). Also a professor.
4. Just a guess, but HN’s patio11 is probably good at keigo. I would listen to anything he has to say about the topic over anything I say.