Is there a way to convert an OpenType font to TrueType using tabular number spacing instead of the default/proportional.
The online converters I have found do not have these options.
You won't find a tool to do this automatically, most likely. If your software does not allow you to choose tabular figures (which I imagine is the case), you would need to open the font in a font editor, change the tabular numbers for the regular ones (by copying and pasting into the right glyph slots), and re-export. You could use FontForge, which is open source for this.
But before you do this , make sure the licence for the fonts allows you to make modifications such as these.
The Fontsquirrel Generator can turn OpenType features into default characters: https://www.fontsquirrel.com/tools/webfont-generator