"ʻElua hua ʻai"
"Fruit" is one of those weird words that can act like a mass noun or like a counted noun. Words like "rice" are a mass noun and never get pluralized. If you want to separate it into countable units, you have to apply a counter like, "two cups of rice". Words like "vegetable" are always counted by their individual units, so that the singular noun is almost always one vegetable and multiple vegetables have to be pluralized. If there is a pile of vegetables you have to use the plural. (The exception is if it is being used as a noun, like "vegetable stew".) But "fruit" can be used either way. If there is a pile of fruit, you treat it as a mass noun and you don't pluralize it. But if it's multiple pieces of fruit and you want to count them, then you have to pluralize it. So, "two fruit" is not correct, and it has to be either "two fruits" or "two pieces of fruit". If you are going to count the fruit, then you need to either give it a counter or pluralize it.
Yeah. Some people don't like using "fruits" for the plural of one type of fruit and only use it for different fruits. So you would have to say, "I ate two pieces of fruit." I don't think "two fruit" is correct anywhere. It either takes a plural or a counter. I think the Hawaiian may be less strict and may not differentiate mass nouns from countable nouns.
1 - ʻekahi/kahi from "tasi" > "isa/esa" (synonym to "satu")
2 - ῾elua/lua from "rua" > "dua"
3 - ῾ekolu/kolu from "tolu" > "telu" (synonym to "tiga", ancient but Javanese still use them)
4 - ῾ehā/hā from "fa" > "pat" > "epat" (empat)
5 - ῾elima/lima from "rima" > "lima" (as you said, an exact fit)
6 - ῾eono/ono from "onom" > "enem" (enam)
7 - ῾ehiku/hiku from "fitu" > "pitu" (synonym to "tujuh", ancient but Javanese still use them)
8 - ῾ewalu/walu from "walu" (synonym to "lapan/delapan", ancient but Javenese still use them [wolu])
9 - ʻeiwa/iwa from "hiwa" (related to Tagalog "siyam", I agree this one is far off)
10 - ῾umi - this one is not related because I think it is also a verb that is used to conclude the last number