@vectoradmin
Ok, it may be a feature, but it lacks a bit of consistency IMHO,
it should either only have 100% -100% value (to indicate the mirror effect) and adjust height in character attribute,
Or display the transformation in layer property only.
A "trick" could be that the value displayed here is in fact the character attribute for text layer.
Not sure what is best, but again, for consistency with other layers, it could display the transformation percentage in the transform pannel for every type of layer, so we don't have to think about different places where to adjust scale.
(thx for fast support !)