Spanish to English Art/Literary Music

Cuentan una historia alevosa que imaginamos como real cuando nos dejamos guiar por los poéticos asuntos que los compositores nos señalan como pistas para entender el retrato de sus traidores personajes. ***Fementidos*** charlatanes que visten ora laúdes, ora claves y mascullan el lujoso lenguaje de los ágrements franceses.
This is from a passage on a website talking about works by some composers -Couperin etc- that will be interpreted by an ensemble (a trio), describing the concepts behind the music. I don't know what the above term means and have been unable to find it thus far. Any help would be very much appreciated, and thanks in advance.