If byte 0 of COB-ID 0x200 is set as a dummy mapping of an dummy int16, byte 1 is automatically set to"-".
Ok so far.

But if byte 2 (next free) is also set to dummy int16 the table gets rearranged in this (faulty) way:

Byte 0 becomes a dummy int8, byte 1 gets the first part of the new dummy int16, byte 2 is automatically set to"-".

Or in other words: When mapping the second 16 bit variable, the first is redefined as a 8 bit variable

Hard to describe, but I think easy to reproduce.