ReadyNAS 104 munin/perl problem

Hi there

I'm using Munin for monitoring my ReadyNAS 104 but after the last Firmware update to 6.9.0 my munin node stopped working.  When I try to start one of the Munin plugins with munin-run I get the following message:

Can't locate English.pm in @INC (you may need to install the English module) (@INC contains: /etc/perl /usr/local/lib/arm-linux-gnueabi/perl/5.20.2 /usr/local/share/perl/5.20.2 /usr/lib/arm-linux-gnueabi/perl5/5.20 /usr/share/perl5 /usr/lib/arm-linux-gnueabi/perl/5.20 /usr/share/perl/5.20 /usr/local/lib/site_perl) at /usr/share/perl5/Munin/Common/Defaults.pm line 9.
BEGIN failed--compilation aborted at /usr/share/perl5/Munin/Common/Defaults.pm line 9.
Compilation failed in require at /usr/sbin/munin-run line 31.
BEGIN failed--compilation aborted at /usr/sbin/munin-run line 31.

So I'm thinking it has something to do with Perl missing some Modules. Unfortunately the new version of the ReadyNAS firmware seems to use a variation of perl that isn't supportet anymore by the regular debian sources cause when I try to

apt-get install perl-modules

I get the following conflicts

Reading package lists... Done
Building dependency tree       
Reading state information... Done
You might want to run 'apt-get -f install' to correct these:
The following packages have unmet dependencies:
 dpkg : Breaks: libapache2-mod-php5 (< 5.6.4+dfsg-3~) but 5.4.35-0+deb7u2 is to be installed
 libdbd-mysql-perl : Depends: perlapi-5.14.2 but it is not installable
 libdbi-perl : Depends: perlapi-5.14.2 but it is not installable
 libgd2-xpm : Depends: libfontconfig1 (>= 2.9.0) but it is not going to be installed
              Depends: libfreetype6 (>= 2.2.1) but it is not going to be installed
              Depends: libjpeg8 (>= 8c) but it is not going to be installed
 liblist-moreutils-perl : Depends: perlapi-5.14.2 but it is not installable
 libsocket6-perl : Depends: perlapi-5.14.2 but it is not installable
 libxcb1 : Depends: libxau6 but it is not going to be installed
 openjdk-6-jre-headless : Depends: libjpeg8 but it is not going to be installed
                          Depends: libfreetype6 (>= 2.2.1) but it is not going to be installed
 perl : Depends: perl-base (= 5.14.2-21+deb7u2) but 5.20.2-3+deb8u9 is to be installed
 perl-base : Breaks: perl (< 5.20.0~) but 5.14.2-21+deb7u2 is to be installed
 perl-modules : Breaks: perl (< 5.20.2~) but 5.14.2-21+deb7u2 is to be installed
 php5-gd : Depends: libfreetype6 (>= 2.2.1) but it is not going to be installed
           Depends: libjpeg8 (>= 8c) but it is not going to be installed
 php5-snmp : Depends: libsnmp15 (>= 5.4.3~dfsg) but it is not installable
 snmp : Depends: libsnmp15 (>= 5.4.3~dfsg) but it is not installable
 tzdata-java : Depends: tzdata (= 2015f-0+deb7u1) but 2017b-0+deb8u1 is to be installed
E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).

Is there anything I can do about this? Is there a munin version that works with the new firmware or is it possible to install older versions of the missing perl modules? I don't want to break the ReadyNAS OS but also I don't want to lose munin monitoring.