Hi,
For Firefox you want to start from here
https://firefox-source-docs.mozilla.org/build/buildsystem/locales.html
You basically need to set up the build system for Firefox, then either
create a language pack or a localized build. For building a Beta or Release
version of the browser, you need to check out that specific version of the
code.
> I'm looking to either pull out a few languages that
> currently don't work well with screen readers and modify them, or to
> create new translations for certain languages that need to be modified
> to make screen readers and speech synthesizers work better with them.
I'm curious on what kind of changes you need to do, and the reasons for
doing them.
Francesco