To answer the last question first – PO files are totally unnecessary for working translations. Only the MO file is required. If people want the PO files then they can get them from the translations website.
GlotPress is a system under the WordPress umbrella that the WP team now use for all of their translations and we adopted because of this. To be perfectly frank with you it is pretty awful in many respects and we live in hope that some of the plans the WP team discussed for GlotPress actually come to fruition.
At the moment ONLY approved translations are included in downloaded MO files. That is the way the software works.
Two of the SP development team are English and the third is American. None of us speak French so we are unable to approve French translations. That requires a member of the community to volunteer top be a ‘validator’. There are quite a few French ‘validators’ bit sadly they seem to work on the bits they eant and then disappear. If you would like to volunteer for the task then just let us know the sign-up name you used on Glotpress and we can upgrade your account. Otherwise hopefully someone else – at some point – will come forward.