Why are you using resize set the font size you want. You may need to calculate what size you want to use. I think I remember I had to save the resolution change the document resolution to 72 because Adobe fonts seem to be baste on points ie 72DPI I could them divide the document height in pixels by the number of lines of text I want to fit over the canvas set the text layer font size. Like( height /5) if I wanted text to be 1/5 document height. Them I could restore the document resolution and the text size would be good.
I would like to create Paragraph Text layers using a script with a specific bounding box. The layer.bounds give me the tight bounding box instead of the values you see on the layer's properties window. I'll try to get the bounding box from transform, that should help.