I managed to change the orientation of the red LCD panel V2.1 to be the same as V1.1 by setting bits 7, 6, and 4 of the memory access control parameter. If you do so, V2.1 can be handled by the very same firmware as V1.1, i.e. by offsetting all graphic instructions by 32 pixels vertically and setting a fixed top scroll area of 32 pixels.
If, instead, you are happy with the orientation V2.1 defines when bits 7, 6, and 4 are not set, then you only need to set a fixed bottom scroll area of 32 pixels and not use any offset in graphic instructions.
These tweaks involving 32 pixels are due to the fact in both V1.1 and 2.1 the manufacturer seems to have set the panel resolution selection pins (GM[2:0]) to 011, which selects 128*160 pixels (refer to the datasheet for ILI9163).
I am not quite sure where the physical difference between panel V2.1 and V1.1 is, to be honest. In order words, I am not sure what the manufacturer changed that made V2.1 incompatible with V1.1, but in the end I am satisfied with knowing how to handle them both in a consistent way.
I will do some more research in future in order to put together material to guide other people on this subject too.
Future versions of the Tiny C2N Monitor firmware will ship with a driver for the red LCD panel V2.1 with some fall-back mechanism (e.g. shorting pins will select a different memory access control so that multiple LCDs can be supported based on the pins that are shorted).
In the meantime I approached 12 eBay sellers in an attempt to acquire some red LCD panels V1.1 for those Tiny C2N Monitor users running the current firmware.