I have a bipa32.svg (see attachment). I want to uniformly change the color of some vertices to blue. Furthermore, I tried using XML, but it always requires constant modification within an interface, which doesn't seem very convenient. I'm wondering if I can convert the image into a text-based format, perhaps store the XML in a single text file, and then make uniform modifications within it (possibly with the help of a script).

Please check in Objects and Layers if the graphic is one single object or a group perhaps. I guess the little dots/circles (vertices) are a group or a compound path which you can easily separate to assign a new color of your choice. Scripting this procedure is not my cup of tea so to speak.

You can isolate all small circles by selecting one and go "Select same=fill color" ,from there you can alter fill and stroke color to your liking (additional Path->Combine raise to top will make the file more clearer - if wanted):

@Polygon How do you select all the black vertices like that? Could you create a complete video tutorial? I greatly appreciate it; I'm quite unfamiliar with this.

Hopefully this. works for you; selecting is done with alt+Selector tool: