Duolingo is confusing me over preposition word order and when to use "teastaíonn", so I am seeking advice.
Some word orders are marked as incorrect or correct in no obvious pattern.
Examples given as "correct" by Duolingo:

Teastaíonn ó bhuachaill uisge
Teastaíonn bia ó fhear
Teastaíonn ceapaire uaim

Which word order is correct, or doesn't it matter?

Teastaíonn uainn éisteacht leis an gcáilin (correct)
Teastaíonn éisteacht leis an gcáilin uainn (incorrect)

Sometimes "teastaíonn" is not used at all to say the same thing:

Tá bia uaithi
Tá cóta gorm uaithi

(if teastaíonn is used for the last 2 examples, Duolingo marks it as incorrect)

My questions:

Is there an error(s) in Duolingo?
Is there some pattern/meaning that I am failing to grasp for noun verb preposition word order/when to use teastaíonn?

Usual word order is verb - subject. The subject is the thing wanted/needed.
So: teastaíonn thing wanted ó person wanting.
Teastaíonn uisce ó bhuachaill "a boy wants water"

Exceptions are cumbersome long subjects (as verbal noun phrases or subclauses with go)
That's why éisteacht leis an gcailín should come after uainn.
Teastaíonn uainn éisteacht leis an gcáilin




teastaíonn uaim and tá uaim are synonyms, I'd think.

Go raibh maith agat!