It is worth pointing out that all the svg editors I am aware of do things (like adding px to font sizes for CSS compliance) that Fritzing that will break in Fritzing. Your best bet is to run edited svgs (or better yet the entire part) through FritizngCheckPart.py to correct that. FritzingCheckPart can be found in this parts making tutorial.
Part creation howto part 1 breadboard and pcb
Peter