Could your use case convert the SVGs to rastor on load? That might be a way of using inline conversion with a 3rd party or even command-line tool, and then dealing with a cache of PImages.
Adobe Illustrator CC (Creative Cloud) is my primary vector editor, I’m sure you could do this in Inkscape, I haven’t.
In Illustrator:
Select text > object > expand.
Outputting the SVG I use these settings:
File > Save As > save as type : .svg > use artboards > range > select artboard number that you want to export
SVG Profiles: SVG 1.1
Type: Convert to outline
Image Location: Embed
CSS Properties: Presentation Attributes
Decimal Places: 1
Encoding: Unicode (UTF-8)
This always gives me a .svg that renders properly, although just as I said before, text is not editable as it is a path.