If You want to publish a new version of Your extension, then You upload the language files of the source languages at the interface of transifex.com, if there are changes at these language files. The source language of Joomla!® is en-GB. Then You enter the new version for the extension at the project details.
If You click at the button for updating (the one with the two arrows) of the project, then a modal window opens, which will show You some text, that the update may take a while. Depending on the speed of the answers of transifex.com, it may take the one or other minute.
A click to Get data starts the update of the language packages. To prevent "accidents" while updating as far as possible, the buttons to close the modal window are hidden.
First BwTransifex fetches the resources of this project, how they are known by transifex.com. Then BwTransifex fetches the statistics for these resources for each language from transifex.com. This is to get knowledge whether there are newly or changed language strings or not.
Until now this is a simple question-answer-game between BwTransifex and transifex.com. transifex.com normally responses quickly. But when the real translated files should be fetched, it is more elaborate for transifex.com, because now the files have to be created from the data pool.
Hence BwTransifex has to request the provisioning of the files. As response for each file of each language an URL is provided, where BwTransifex can look, if the file is provided and where BwTransifex may download it. Especially the provisioning of the files by transifex.com may last, depending on the server load.
With this step the language files are created if needed. The update servers for each language are created and also an update server of type collection is created.
If the language packages are created, the buttons to close the modal window are reactivated and You may close the modal window.
If errors occur while updating the language files, they are shown at the modal window and depending on the severity of the error the update is going on or is cancelled. If the update is cancelled, this should happen in a well-arranged manner, so that the modal window may be closed.
If an error occurs, which is not even known and which I don't catch so far, it may happen, that the modal window may not be closed in an well-arranged manner, because the buttons to close don't appear. In this case, only the back button of the browser may help. In this case I would be very grateful to get a note at the forum, if possible with a description as accurate as possible. As a developer You know, what I mean.
BwTransifex remembers the statistics of the previous update. If this is the first run, there are no previous statistics, so the update takes place. New language packages also are created, if the option Update always? is set. But You should activate this option only if necessary.