Rashi on Numbers
וַתִּלָּחֵץ — the Niphal form denotes that SHE PRESSED HERSELF.
Rashbam on Numbers
ותלחץ את רגל בלעם, which resulted in Bileam becoming partially lame as we know from 23,3 וילך שפי, he walked with a limp.
Rashi on Numbers
וַתִּלְחַץ — the Kal denotes that SHE PRESSED something else — viz., את רגל בלעם BALAAM’S FOOT.