Ok, I think this is the final deep dive for a while 
I found this study looking at M21, M31, T-58 and WB-06 in bread fermentation (among other yeasts). It’s quite interesting, including among other quantification of specific esters. Based on their data, I find it doubtful that (a) M21 could be T-58 or (b) M31 could contain WB-06.
Furthermore, I think the key to determining M47 would be the flocculation. MJ states that it is “highly flocculant” (4/5 for both flocculation and “compaction”) which doesn’t match pure T-58, but would match BE-256. On the other hand, it has lower attenuation (73-77%, doesn’t ferment maltotriose very well) than you would expect from either BE-256 (82-86%) or Lallemand Abbaye (77-83%). As it is said to exhibit “spice and fruity esters” and “fewer phenols than Belgian Ale”, it is likely not pure BE-256 which is POF negative. My guess is therefore that it is T-58 + BE-256, which gives some spice, lots of esters and also flocculates and might attenuate better than pure T-58. Incidentally, BE-256 was originally called “SafBrew Abbaye” until this was changed in 2015 (likely after the MJ names were fixed). While much of this is speculation, it would fit with the general design pattern of co-pitching to improve flocculation/sedimentation.
So summary of speculation for the new “Belgians” introduced in 2015:
- M21: Lallemand Wit
- M31: Lallemand Belle Saison + Abbaye
- M41: Fermentis WB-06
- M47: Fermentis T-58 + BE-256