Why not using subfolder?

[ronrun]

Is your feature request related to a problem? Please describe.
I installed this package, it seems good. But after sync to database, the "group" column of translations table only use the file name.
For example,
/lang
/en
/common
header.php
column_left.php

The group column is header and column_left. Then I sync to file from database, the subfolders are gone.
/lang
/en
header.php
column_left.php

I think the group should be "common.header" or "common\header"