Brass fingering plugin gives wrong figures for transposing instruments

Windows 10: MS ver 2.2.1 Tromboneslide.qml
This plugin gives the wrong valve numbers! It appears that the plugin is internally transposing from Concert pitch to Bb and giving those fingerings. A C on the stave in concert pitch is given as valve 1. To play a C is 0, no valve. If you are on a Bb instrument you need to play a D so 1 is correct (for high D anyway). However, I am using an Eb instrument. For me a concert C is played as an A and the fingering is 12.
I suggest the plugin is modified so that it does not transpose in itself but works on notes showing on the stave on the current page - the user can take care of the transposition. There are many people using transposition instruments who don't only use Bb.
It is also confusing that the plugin list identifies this as "brass fingering" which was the name of a previous plugin (version 1.0) so it is not clear which one is in use.
One further comment, I don't see any option to give trombone slide positions.
I have found this very confusing, please be kind if I have got my transpositions inside out, I am going to have a lie down!