So mechanically yes, pneumatically, maybe...
Not necessarily.
The answer is : It depends.
Not all Scharfenberg couplers are compatible with each other (let alone with another manufacturer such as Dellner). They all operate a similar principle of male and female cones and latches in the coupler head, some form of draft gear behind and a centering mechanism, but there are some crucial differences.
Electrically as stated - the electrical autocouplers are not always in the same place - some couplers have one on top of the coupler head, some have them split and mounted either side of the coupler head and others have them below (with no guide horn). The ones that have them mounted below are not mechanically compatible with ANY autocoupler with a guide horn as it would smash into the electrical coupler and wipe it out.
However you can mechanically couple up a similar coupler where one has an electrical autocoupler and one doesn't. An example would be a TGV to a Eurostar. TGV nose-end couplers have an electrical autocoupler (for running in multiple), but the Eurostar nose coupler is purely mechanical (of course, with brake pipe connections).
Mechanically, it is not as simple either. Some Schaku/Dellner couplers have a single latch system, and others have a double latch. The main issue being that they are not all mounted at the same height above the rail head. While they can take out a little bit of relative height due to wheel wear, and coupling up to a set with no air in the suspension, they are not all going to work. EDIT: There is a high speed standard height of something like 1050mm to a reference datum, but without my reference data handy, I can't say exactly. However that standard is not in force on non high-speed lines. At least it is not mandatory.
The answer to the specific question asked above would depend on a few factors then. The height above rail they are mounted at would be (I assume) either identical or very similar. The mechanical compatibilty would then come down to what exact type of head is mounted on the couplers. You can have the same headstock mount, support spring, centering device and draft gear, but two different heads.
I don't know much about the specifics of the trains mentioned but maybe that clears up some of the confusion.