Depends how you are approaching the challenge of a multi lingual app.
You could create seperate apps per language. This will be the most complete app language coverage wise.
In Sense not all labels are app to be set by expression. some chart types do and others don't. also sheet names are currently static labels so the question is how much of the app needs to be in a particular language.
If you can be flexible then using the setting of labels,titles, sub titles by expression can be a good way to go as you only need to create one app. the only issue is you don't have 100% coverage at present.
There is only this extension http://branch.qlik.com/#!/project/583bf018bc27ce82336c93ad that allow you to have multilanguage on QlikSense.
This extension allow you to change the label also where the label isn't an expression because this extension works at html level.