What would "Disintegrant", "Ammonium", or the units of measure "glass" or "gl" mean in a non-American book?

"Ammonium" is probably "baker's ammonia" or "ammonium carbonate" -- this is an old-school leavening agent, which has mostly been replaced with baking soda & baking powder in modern cooking.

A "disintegrant" is the opposite of a binder. Without context, knowing what it is specifically talking about is hard to say. In pharmacology, a disintegrant is used in oral tablets to make them rapidly break up when they get wet. Most "chewable" oral tablet medicines have a disintigrant to help them quickly break up when you put it in your mouth.

Edit: Based on the example recipe that you added, I'm going to guess that it's also reference to some kind of leavening agent. Whether it's intended to be baking powder, baking soda, or is also a reference to baker's ammonia, I'm not sure. Seems like it would be necessary to experiment a little bit to determine--but I think it's safe to say it's probably one of those leavening agents.

I presume that "gl" is an abbreviation for "glass" and both refer to the same unit. This other question indicates this is a common Russian unit of measure (is your cookbook Russian?). There is no accepted answer on that question, but the answers there all indicate that it is somewhere between 200ml and 1 cup.

Given the recipe, a very likely guess for "disintegrant" would be some leavener, preferably baking powder. The reason I am suggesting this is that cookie recipes without leaveners are rare, and this one looks like it would have a good chance of turning out doughy if no leavener is added. The "1 bag" measurement supports this theory - in many European countries, baking powder is sold mostly in single-use sachets formulated for roughly 500 g of flour.

I have no idea what linguistic misunderstanding is needed for getting the word "disintegrant" placed where "baking powder" should have been. But it is a logical ingredient from the recipe point of view.

Gl likely" gill" if a liquid measure. Unfortunately Wiki lists two kinds : British gill = 142 ml . American gill = 118 ml. Go figure .

"disintegrant" is probably dough conditioner, though "1 bag" is odd.

elsewhere in the book, "Disintegrant - 1 bag (10 g)" appears in a recipe with "Flour - 2 glasses 250 g" so it's in the same proportion as the Apple Cookies recipe (1:50 by weight, or 2%)

that 2% is right in the middle of the range that dough conditioner would be added

so "Disintegrant - 1 bag" is 10 g of some unknown dough conditioner that was available in an unknown place somewhen between 1950 and now

[edit] a simpler answer is baking soda or slaked soda, though it doesn't make any more sense in the context of "1 bag"