I've just run parts of the vttest suite against the AnsiTerminal program. Two of them failed:

The test for ANSI colors revealed that the terminal can't display the color blue, neither the bright, nor the "normal" flavor. Magenta is displayed as red.

The other test is called character position absolute (HPA), which should display a box of asterisks, but the left and right edge of the box are depicted the wrong way:

Terminal type is ANSI. I am using an Olimex board, but the guys from Olimex said they were not competent in this matter.

** FabGL — Serial Terminal                           **
** 2019–2022 by Fabrizio Di Vittorio — www.fabgl.com **

Version           : 1.6
Screen Size       : 640 × 480
Terminal Size     : 91 × 36
Terminal Type     : ANSI
Serial Port       : FabGL Terminal: TX=2 RX=34
Serial Parameters : 115200,8N1 flow=None

UPDATE: The blue-blindness is apparently not related to the hardware, as the Space Invaders game shows no such problems. Both white, and light blue objects are displayed correctly.