koi8u2ruscii is old format map and, like koi2alt, it has not to be gzipped because command "consolechars -f RUSCII_9x18 --acm koi8u2ruscii" produce error output:"MUST be a regular file". After gunzipping koi8u2ruscii.gz everything is OK.
Fixed in console-tools-19990302-17. Thanks for the report.