I think this might just be an error on BS01’s part? This is what Swamp of Secrets has to say about the Toa Mata being in Karda Nui:
“These were what the Matoran called ‘avohkah,’ and the reason the Toa were there. At first, the villagers who labored in Karda Nui thought the place was just prone to violent lightning storms. But after more than a dozen Matoran were killed by lightning strikes, the rumor started that the bolts of energy were actually hostile and intelligent beings. The Toa’s first few encounters with the avohkah seemed to verify this. The lightning bolts avoided obvious traps and seemed to go out of their way to do harm” (94).
No mention of “energy spikes” so far as I could find in the book, but the avohkah fit that description, both in terms of being energy and in causing harm. Could be that someone mistakenly thought that the byproducts of the Matoran’s labor (the energy spikes) and the avohkah were two separate phenomena. Or it could be that the concept of the energy spikes comes from the numerous Ask Greg answers, and it simply isn’t cited.
I don’t think so. It’s fairly vague on how they were specifically defeated, but far as I can tell, the avohkah were just largely defeated by trapping them in glass or Gali blasting them with water.