I noticed a severe translation bug in Apper's german catalog:
The strings "The following package was found" and "The following packages were found", are translated with "Das folgende Paket ist nicht auffindbar"/"Die folgenden Pakete sind nicht auffindbar", which means the exact opposite, i.e. "The following packages were _not_ found".

From Apper's po/de/apper.po:
#: PkSession/ReviewChanges.cpp:50
msgid "The following package was found"
msgid_plural "The following packages were found"
msgstr[0] "Das folgende Paket ist nicht auffindbar"
msgstr[1] "Die folgenden Pakete sind nicht auffindbar"

I'd suggest to change it to this:
#: PkSession/ReviewChanges.cpp:50
msgid "The following package was found"
msgid_plural "The following packages were found"
msgstr[0] "Das folgende Paket wurde gefunden"
msgstr[1] "Die folgenden Pakete wurden gefunden"

PS: I hope I reported this at the correct place. If not, please point me to a better one... ;)

Reproducible: Always

Steps to Reproduce:
1. Run e.g. "apper --install-package-name kile" with a german locale
2. click on "Continue"/"Fortsetzen"
3. Apper searches for the package, and will present you with a list of found packages

Actual Results:  
The dialog to review the changes (select/deselect packages to install) has the header "The following package was not found"/"The following packages were not found" in german.

Expected Results:  
The dialog to review the changes (select/deselect packages to install) shoudl have the header "The following package was found"/"The following packages were found" in german as well.