L'ar'er, meaning an undermining of balance, has never been my favorite verb, because it goes twice over two consonants that we Americans can’t pronounce well.  Even in English, I was never sure whether to pronounce the verb “err” like the first syllable of “error” or like the first syllable of “ermine.”  But what l'ar'er does have in its favor that verbs like undermine or destabilize don’t is its ding-dong, seesaw , shikshukish repetition.  It brings to mind — to my mind, at least — an effort to weaken something by joggling it back and forth.