Singular/plural forms of subjects with “respectively”

Solution 1:

The first sentence is for certain ungrammatical. If we remove the prepositional phrase we are left with

The schema are called C and D, respectively.

This should be

The schemas are called C and D, respectively.

This leaves the question of whether it is "buffer" or "buffers". Let's examine just the sentence's subject:

1. The schemas of the A and B buffer
2. The schemas of the A and B buffers

I would parse the first as saying that there is an "A and B buffer" which has several schemas, whereas I would parse the second as saying that there is an "A buffer" and a "B buffer", and between them they have several schemas. Interestingly this ambiguity goes away in the case of

The schemas of the A buffer and the B buffer

While this ambiguity is resolved by the use of "respectively", it makes the sentence somewhat awkward to read, if not ungrammatical. To avoid this ambiguity I would recommend either

The schemas of the A and B buffers are called C and D, respectively.

or

The schemas of the A buffer and the B buffer are called C and D, respectively.