Increase size of non western font in mixed font documents

[simian]

Hi,
I need to use English and Thai in the same documents. At the same font size, Thai characters are smaller than Roman characters, which makes them hard to read. Example : https://ibb.co/DL2P8vK

When I increase the font size of the document to make the Thai better readable, the Roman characters become too large. So I have to manually select the Thai parts and increase only their font size. This is not only time consuming, in many applications (eg text editors like gedit, xed or cherrytree), it isn't even possible.

Is there a way to increase the display size of Thai characters system-wide so that in all applications the size of the Thai characters would be more in tune with the display size of the Roman characters (preferably a bit bigger)?

I followed the instructions from https://forum.xda-developers.com/t/tuto ... le.990853/ to increase the size of the characters in the font file itself, but that didn't work. Although I double-checked that all characters were selected, not all characters were changed, the spacing between the characters is now off, and the position of modifying characters above the letters is wrong.

Suggestions?
Tnx!

mint 19.3 mate