Tested on a (win32) 3.7 (Squeak3.7-5989-full) and 3.8 (Squeak3.8-6665full) full image.
It looks like the XML parser is by 'mir' and is included in each release I think.
I am currently woking on some text support, not very pretty I'm afraid! The example svg you provided looks ok(ish) now!
New release coming soon....
Thanks for the encouragement!