Hello,
I saw your message on the Guix mailing list.
I just want to let you know that I created a package for Mozilla
Thunderbird. You can find it at this address:
https://bitbucket.org/julien1001/guix-packages/src/default/julien1001/packages/thunderbird.scm
The package actually uses the binary version of Thunderbird, built by
Mozilla.
In fact, two packages are available: one in version 52, the other one
in
version 60. Both use the French version of the binary.
With a little bit of adaptation, you should be able to create a package
for your preferred language.
Best regards,