Oh man, i´m all for " get them while their young", but i don´t think you can actually train Tatzlwyrms to do anything. I didn´t find Stats for them, but i think they are simply to stupid and predatory, much like Owlbears.
So you could maybe use them to keep a "Royal Reserve" cleared of people or at the most try to restrict them to one of the islands at the ford and use them as "watch-wyrms", but sooner or later they´ll go hunting on the wrong side of the river.
Handle Animal wouldn't work. They aren't animals, they are intelligent (Ok, 5 int) dragons. How long does it take to raise a Tatzlwyrm to adulthood?
From the Stolen Lands AP, "Female tatzlwyrms attract males with scent signatures, inviting them into their dens. After mating, the female hibernates for upward of a month during gestation until she produces eggs, while the male guards the nest. During mating season, tatzlwyrms maintain small, temporary family units, but hatchlings only stay in the nest for a few months before being driven out. Afterwards, the mated pair breaks up, often violently. Vicious in mating as in all things, nearly half of all tatzlwyrm pairings result in the death of one or even both participants. Tatzlwyrms average between one and three surviving whelps out of an annual clutch of eggs, so they rarely multiply rapidly."
It would seem that hatchlings only stay in the nest a "few months" and are probably able to take care of themselves after that. It's odd that they don't mention the average number of eggs per clutch, I'm would imagince that the survival rate would be higher in captivity than in the wild.
Handle Animal wouldn't work. They aren't animals, they are intelligent (Ok, 5 int) dragons. How long does it take to raise a Tatzlwyrm to adulthood?
I just found this from the Stolen Land AP, "Tatzlwyrms live between 20 and 30 years if allowed to survive to old age, reaching full size after only 6 months of rapid growth."
I also noticed that they have the draconic language, usually in the language section they indicate if a creature is unable to speak they note that in the language section of their stat block.
Vegepygmy's can be used as an example, they have Languages Undercommon, Vegepygmy (cannot speak).
With Tatzlwyrm having Language Draconic, IMO means that they can understand Draconic and might speak Draconic. Tatzlwyrms don't have a very hign Int. so their speach, if they chose to talk, would be very simple to say the least.