Good day, Susan:
Thank you for the question.
First, I would say you are right on the money with your analysis of how to treat a single fully capitalized literary word that occurs between two math expressions. The single-word switch indicator should precede the capitalized word indicator and the word itself. The following space would terminate the effect of both the single-word switch indicator and the capitalized word indicator.
Second, without addressing a specific example, I cannot give you a cut-and-dry answer regarding typeform on a single word within a Nemeth Code, because the use of typeforms within Nemeth Code depends on the meaning conveyed by the tyepform. For example, in the circumstance outlined on page 11 of the Guidance for Transcription Using the Nemeth Code within UEB Contexts, the typeform must be retained because its meaning is mathematical.
In the rare circumstance where you had to retain typeform for a clearly literary word that was located between two mathematical expressions, the single-word switch indicator should precede the typeform indicator and the word itself.
If you can, please do share a specific example where a typeform must be retained for a single literary word that occurs between two mathematical expressions.
Thank you again for the well-expressed question.