Hi there. I'm pretty sure it's a known issue that special effects, like silence, don't trigger when a weapon is thrown, even if it has the Thrown property. I know it's been discussed here previously, but am not sure if Larian have confirmed it's by design rather than a bug. (Personally, I think that as long as the weapon has the Thrown property, or the thrower has the feat to throw other weapons that's not in EA, then all effects should trigger when thrown just as they would if used in melee).
I hadn't realised finesse thrown weapons use STR for attack. I've not played around with throwing weapons a lot, and I guess for dex characters many folk would use a bow for better damage and dip-ability (though of course a dagger should be a totally valid choice for RP if nothing else). Another forum member might be able to comment on whether this issue has been reported previously.