An "indecent assault" is "trying to kiss or touching a woman you don't know (or who is not willing)" or "to cop a feel"
I usually find it transalted by "sexuálny útok", but it sounds too harsh to me, or even by"pokus o znásilnenie" is not that too much?
Likewise, "pinch a bottom" is translated with "štipnúť" which is idiomatic in English.
How do you say in Slovak if someone touches a girl's bottom on a crowded bus?
Also, do you happen to know what is the Slovak for "assault and battery"? Webslovnik has:
úmyselný násilný útok so vztiahnutím ruky
what does that mean?
battery can be a punch or a kick, do you know the right therm? usually it is translated by "ublíženie na tele", but that is "bodily harm", something more serious.
Is a "modrina" = ublížnie na tele ?