I think it is most likely Yasuhikotakia lecontei as you said. They're rather rare in the trade.
It could be a Yasuhikotakia modesta, but they tend to have very dark blue bodies (and red or yellow fins). The photo doesn't show that much blue, but it could be stress or a washed out photo.
Most of the Yasuhikotakia loaches are rather aggressive, and will pick on your snail . Probably to the point of killing it (if it is not a large snail, they'll eat it outright).
From the pictures in the bag, the one of the left and on the righ look thin. You should try to fatten them up and potentially treat for internal parasites. www.loaches.com has some treatment recommendations. The lower picture looks much better though. It is not uncommon for loaches to have some internal parasites, and/or be thin from shipping and holding in fish shops.