I'm working on the new documentation wiki, and just grabbed the old instructions for the Character Importer.
There are a few things that immediately jump out at me. Some will need adjustments in the wiki, some will need adjustments inside Foundry.
http://sr5-foundryvtt.privateworks.com/index.php/Chummer_Character_Importer
The SR5 system allows users to import characters from Chummer5a.