When I downloaded a translated PowerPoint file (JP to En) , the font size was smaller comparing to the source file.

Since English sentences tend to be longer than the Japanese sentences, we apply a macro function to auto-adjust the font size to minimize layout distortion (currently it is applied to the text boxes only).

So the font size change probably happened because of this auto-adjust function. 

Since the macro settings can't be turned off, if the size is too small, please adjust the font size after downloading the translated file.