That's pretty impressive what you are doing with exported SVGs, but I can't help you, sorry. OK, to be honest it's more like I don't want to, but not in a bad way. I treat SVG as a purely presentational format, any traces of semantics you manage to extract from them are just side-effects. Adding ids, classes, maybe some meaningful grouping is a way to improve SVG, adding geometry, which is not displayed is a way to make SVG worse. I want exported SVGs to be as compact, simple and human-readable as possible.
Also please note, that if everything goes according to the plan, in the next major update there won't be any wards at all, not only in SVG, but even in the code. Maps will consist of independent blocks (grouped into districts, similarly to current wards). This means that BSP won't be involved in street generation.
When the desktop version finally arrives, its saved files will contain all the geometry there is. I was going to use JSON for that, something pretty close to GeoJSON. I hope it will be convenient for all who want to process such data themselves.