When I installed from repositories KMyMoney in Ubuntu 10.04 from Clay Weber repository (https://edge.launchpad.net/~claydoh/+archive/kmymoney2-kde4). I couldn’t change language to Spanich.
I did it reading that:
To localize you will need to download the appropriate kmymoney.po file from http://websvn.kde.org/trunk/l10n-kde4/-country_code-/messages/extragear-office/ (replace -country_code- with the correct one for your locale e.g. es would give http://websvn.kde.org/trunk/l10n-kde4/es/messages/extragear-office/) and then, either by switching to root or using sudo, do the following:
Copy the kmymoney.po file into /usr/share/locale/-country_code-/
In that folder run as root:
$ sudo msgfmt kmymoney.po -o LC_MESSAGES/kmymoney.mo