It's been awhile since I set the VPM "virtual version".
There isn't a lot of X-Speech in these custom ROMS. They tend to favor saving it for spice. Like T2, the only vulgar speech in T2 is when you hit the lower left eject hole that has the random award.
In the "vulgar version" there is one extra random award in the list that appears in the DMD and if it is selected by the machine, then you get to hear Arnold say, "F**K You ASS*H***. However, the phrase is always visible in the random list that appears when hitting this eject hole. Very formal.
Demolition Man has a couple of phrases and I don't know if there are more than that. There is dirty blue when you tilt the machine, not very useful for honest players I admit, and at the end during the MATCH sequence Sly tosses a cuss.
I hope bringing up the subject of "vulgar speech" on the H6 ROM wasn't misleading to you.
I think its a matter of setting the Adjustments to:
Vulgar Speech: ON
Match Speech: ON
The machine might need to be set to FREE PLAY.
Do you see FREE PLAY in the DMD Attract Mode?
If you hear no cuss during the MATCH sequence (or on a TILT) and the speech settings are both set to ON and there is no FREE PLAY visible in the DMD during attract mode outside of play, then also try setting the pricing adjustments to
FREE PLAY: ON
With T2 the FREE PLAY needs to be enabled so that the single vulgar feature doesn't appear in public commercial arcades, so that's probably the same rule for Demolition Man.