Brownies are CR 3 Tiny fey with calm animal, spell-like abilities, darkvision 30 ft., evasion, hide in plain sight, low-light vision, uncanny dodge, and wild empathy.
Boggarts are CR 5 Small fey (shapechanger) with confusion, electrical bolt, deflection, invisibility, immune to electricity, low-light vision, magic immunity, tongues, and unstable form.
there are so many creatures that could be put into a woodlands book, but yes these 2 would be a cool addition. need to check out that link when i'm at home...
In all fairness, they aren't actually called desmodu. But if you look at the nycter and then look at the desmodu, I'd say there is definitely not much difference.