Hello Count, it’s indeed my fault for writing poorly and not making myself clear, so I apologize to you, especially for the delay in my response! :)
Doubting whether I had made a mistake, I went to check in my old theory book. "Simple" time refers to a time where each movement is divided into two parts, while compound times (compound, not complex!) have a ternary subdivision.
Thus, "simple measure" at 2 beats is 2/2, 2/4, etc., and at 3 beats it’s 3/2, 3/4, etc.
Compound measures at 2 beats are 6/4, 6/8, etc., and at 3 beats it's 6/16, 9/4, etc.
Then, the irregular groups. Groups can be irregular due to formation (groups of 5, 7, 9 notes) or irregular in relation to the unit of time. As you rightly said, the sextet can be considered as formed by three duos or two trios.
The duo is a regular group in simple measures with binary subdivision, while it is irregular due to reduction concerning the time in a compound measure. The opposite applies to the trio, which is irregular due to excess in a simple measure and regular in a compound measure.
The sextet, deriving from the trio or the duo, if played in a simple subdivision, is irregular, whereas if played in a compound subdivision, it is regular.
Oh, of course, I wrote all this not to act like a teacher, but to be precise, since in DeB you cannot stray from a comma! I know you understand these concepts better than I do; it was just to clarify... :) Regards.