How to contribute translation changes

[skhrshin]

Hi, I'm a member of a development team which customizes Canvas for Keio University Shonan Fujisawa Campus, Japan. Some of changes we have made are not specific to our system, so we want to contribute them to the original Canvas project. First, I'd like to push some advancements in Japanese translation because that would be easiest to merge, but as https://github.com/instructure/canvas-lms/issues/2004 is saying, the Transifex page is not accessible. We have edited config/locales/ja.yml file directly by hand, but we guess that is actually not the right way to persist changes and there should be some kind of master data probably in Transifex we cannot see. How can I contribute our translation advancements?