config.xml - load two translations (qt_pl.qm and ifw_pl.qm)

Hi

In config.xml file is possible add two or more language files.

<Translations>

<Translation>ifw_pl.qm</Translation>

<Translation>qt_pl.qm</Translation>

</Translations>

but it not working, 

For my installer J need load two files:

ifw_pl.qm - there are all translations but not buttons "Next/Cancel"

qt_pl.qm - there are missing translations for buttons "Next/Cancel"