Aurebesh spellings in game

I spotted this on the galaxy map (apologies if planet names are spoilers but these two really shouldn't be). In white font on black are screenshot crops from the game, below in black font on white are my additions.

In game, the Aurebesh uses separate characters for "T" and "H" in Dathomir and "S" and "H" in Kashyyyk. But Aurebesh has the characters THESH for the letter group "TH" and SHEN for the letter group "SH". The bottom row is how I expected them to be spelled. I haven't checked every script in game for this but these are the most obvious examples.

Why are Thesh and Shen Aurebesh characters not used in the planet names? Have some Aurebesh characters been de-canoned?