set aside, store

える(たくわえる) Setting stuff aside for a rainy day. Used about good things. Also – in contrast to 貯める、 蓄えるis used about important things:bears accumulating winter fat for their hibernation. One’s retirement nest egg.
(ちくせき) Accumulate. Used about bad things mostly – bills or stress pile up. But it also can be good, like the compound interest or accumulated knowledge.
める(ためる) Store up unimportant things; things that you didn’t deliberately seek out but accumulated nonetheless:change from your couch cushions. “I left the bathtub full for you if you want to use it.”
まってきた(とまってきた) Half-done things pile up. Always bad. Bills, two weeks’ worth of half-done homework that is all due tomorrow, ohhhh shiiiiittt!!!
(とどこおる) Unlike 留まってきた (weeks or months worth of stuff piling up)、 滞る is used about bad things that are piling up right now:traffic jams, delays. The idea of 滞る is that things which are currently in progress. . . .don’t progress.
なる(かさなる) Used when a series of bad things happen to you. It never rains but it pours. Yesterday my boyfriend dumped me, then I lost my cell phone, and now I just lost $200 playing pachinko.
ねる(つみかさねる) A super-strong version of 重なる。 積み重ねる is like, you have such bad luck you’re suicidal.