I use a MC15SmkII, which is seems much the same as the Salsa,
though it may be some details have changed, in a Rega RB250.
The treble is not on the reticent side, some records can tend to sibilance,
but I've never found this apparent on instrumental music, only on what
can be described as overproduced popular music.
I might as well state the obvious - Do you have to look at your arm set up ?
Well on a basic level of course you do - and you should know how well its set up.
You say "a bit harsh". Is this a tonal thing ? Or the dreaded mistracking harshness ?
If the former BN's suggestions are good, the latter - a different can of beans ....