As an N Scale guy, getting a chuckle to see HO guys chatter about decal thickness. Welcome to our world!
The topic of the thickness of Tichy decals comes up from time to time over on TheRailWire.net. If I was to summarize it? I'd say, what is clear is that thickness is:
a) somewhat related to the specs of the rig, paper and ink used,
b) somewhat related to the specific image and color sought to reproduce, and
c) somewhat related to communication between the printer and the client.
So it would be wrong to make a general statement of "Tichy's decals are too thick". Sure, for some decals, of some images, on some settings, on some surfaces, Tichy might not be able to produce what you'd like. For us N scale guy, we can say that about nearly all decals.
But for the sake of compassion, I will share some sample data posted back in 2017 on TRW comparing thickness of Tichy's inkjet decals to say the Microscale screen printed water slides looking at very comparable black ink datablock on new PFE decal sets:
Using my ol' Starrett Vernier micrometer caliper, I have The Tichy backer paper, adhesive and carrier film at a dead 0.0090" and over the datablock, a 0.0100". So a black only ink height is just 0.001"
Off topic: All this leaves me thinking the scale model decal market might still benefit from new technology - one that can yield smaller / finer fonts at higher resolution, and not dependent on the limitation of ink jet or silk screen. Kind of intrigued by the advances in intaglio microprinting and advanced inks, and wonder if such can be applied to develop waterslide decals ... but I'm certainly no expert here!