I decided to return to using the locators/null objects as they required less adjustments than the mesh/solids (the mesh/solid would mirror and flip the text when it was parented). For the most part, the only adjustments the locator/null method needs is -90 degrees in rotate x, and maybe a few minor adjustments in the other rotates on the null object or position attributes for the text layer.
I'm going to continue to experiment with this method after rendering out a scene with more complex camera movement to ensure this works correctly. I also have been trying to find some fonts for certain languages that are missing characters from the chosen font (hence why in German some words have a normal 'a' rather than an 'ä' at the moment). So far I think the font 'Noteworthy' has been the most successful for Bulgarian in comparison to the others that I've tried.