The svg renderer only accepts fonts declared as such:
font-family="DejaVu Sans" font-weight="bold"
A lot of vector editors (Illustrator, sometimes Inkscape) output their fonts like that:
The renderer falls back to the default, if fonts are declared as in the second example.
If this would be fixed, a lot of svg would then properly display the chosen font
T64987: librsvg misinterpret quoted font family names that contain whitespaces
T40589: Rendering of SVG text too large (font sans)