When a template or module needs to know about all languages of a multilingual SVG file,
it is necessary to browse somehow the SVG code of that file.
That is done e.g. by the File Description Page on Commons,
or by tools like the Toolforge Translator, each time when the file is accessed,
making sure that the list or table is always at the current state.
But currently a Lua item like "mw.title.getCurrentTitle().langlist" does not yet exist,
displays shown on the description page have to be maintained their parameter list
anytime when something is changed depending the embedded languages, to be up-to-date.
Of course, such a title object needs physical file access and is therefore not cheap,
it must do quite the same as is done when the description page is displayed.