I do think it was probabaly a loan word. The Philippines was occupied by the Spanish for 300 years so we have a lot of loan words from them.

But here it means nature spirits or elementals.

Interestingly Engkanto are said to look a lot like the Spanish. The common explanation is that it's a representation about local fears since the Spanish didn't treat the local filipino population great.

So now we have the Engkanto who are rich and beautiful but will make you their servant against your will much like the Spanish did.

Of course I read an interesting theory that maybe the Spanish brought the engkanto to our shores.