Franck Hi! Thank you for your interest in helping out with translation. For the parts you mention, it is handled by different projects/entites so you have to ask each project about it.
Franck in Software Center : the panel "parameter"
Software center (solus-sc) is developed by Solus Project but it is in process of being deprecated so we don't really accept any new translation.
Franck in keyboard/shortcuts : the description of shortcuts
Where do you see this? If this is the "Settings" apps in Budgie, then go to Buddies of Budgie website for more information.
Franck in Budgie Hotcorner settings : almost all...
For Hot Corner, please head to Ubuntu Budgie website as it is part of budgie-extras. Cheers!
