I’ve been exploring this for a couple years and have been stalled for a few reasons. For the same reasons, you’re not likely to get satisfactory answers here.
My understanding is that the author of the papers @ryan_durand mentioned is the only person in North America with useful experience with dandelion microspecies, and he wants to expand on those papers in the future but he’s busy with a lot of other botany work as well. There are a decent amount of people in Europe who are confident in their ability to identify microspecies within their countries, but they’re generally not interested in identifying North American dandelions because they have no idea what species options there are; the plant could have originated from anywhere in Europe and they only have experience with the microspecies in their own country. I’ve found a lot of resources for identifying sections/microspecies but they have the same issue; they’re only made for smaller regions of Europe so the applicability for North America is limited when we know so little about the options. Not many people with expertise are active on iNaturalist because it’s American and in English and they may have their own national biodiversity documenting programs, and even fewer use the forum.
Ultimately for iNaturalist’s taxonomy I don’t think it makes much difference what anyone’s opinion about the various options are. INaturalist curators aren’t supposed to create new taxonomy systems; we have to use existing ones. For plants iNat follows POWO, which rejects T. officinale. Additionally, iNaturalist needs a taxonomy that works globally. The two options we have are the Eurasian system, which is already global, and the North American system (FNA), which is outdated and not adaptable and taxa from other continents can’t be worked into it. I tend to be a lumper and I think the dandelion microspecies are excessive but I still think iNaturalist needs to be using the European system. If someone wants to do a ton of genetic and morphological work and publish a new global taxonomy that’s closer to “sections ~= species” that would be amazing, but it doesn’t exist now and I can’t imagine anyone wanting to do it. Currently on iNat we are using a messy mishmash of the two systems.
Relevant forum thread:
https://forum.inaturalist.org/t/overlooked-dandelion-diversity-in-bc-and-everywhere-in-north-america/3808
And flags:
https://www.inaturalist.org/flags/526232
https://www.inaturalist.org/flags/535033