Description of Problem:

There are assorted problems with how 'man' configuration is handled.
It starts with this fragment of 'man man':

              Specify  the  configuration  file  to  use;   the   default   is
              /usr//etc/man.config.  (See man.conf(5).)

Interestingly enough there is no "see man.conf".  There is 'man man.config'
and this one for a change says:

FILES
       @man_config_file@

Ahem...

Checking with 'strace' what is actually consulted we can see

open("/usr//etc/man.config", O_RDONLY)  = -1 ENOENT (No such file or directory)

and this even includes "//" as 'man man' says.  It is true that this is
followed by attempts to open "/etc/man.conf" and "/etc/man.config" but the
content of the later seems to be taken into account or ignored depending
on some circumstances I cannot figure out.  In particular PAGER used may
end up either as '/usr/bin/less -isr', with output looking ok, or as
'/usr/bin/less -n' which will display escape sequences on a terminal.
A workaround for that is to set MANPAGER variable in an enviroment.

Further we can see in /etc/man.config

MANPATH /usr/local/man
MANPATH_MAP     /usr/local/bin          /usr/local/man
MANPATH_MAP     /usr/local/sbin         /usr/local/man

where /usr/local/man does not exist for quite a while replaced with
/usr/local/share/man.

And there is also this comment:

# NROFF is defined as "groff -Tascii" or "groff -Tlatin1";
# not only is it superfluous, but it actually damages the output.
# For use with utf-8, NROFF should be "nroff -mandoc" without -T option.

Is this indeed correct and a reason why non-English man pages are coming
mangled?