[Tlhingan-hol] mutually subordinate clauses?

[De'vID jonpIn]

I suspect that most people would understand the following sentence,
but is it grammatically aberrant?

{mapawbe'chugh wIHIvlu'pu'mo'} "If we do not arrive, it is because we
have been attacked."

Does it need to be recast as something like one of the following?
{mapawbe'chugh wIHIvlu'pu'mo' mapawbe'}
{mapawbe'chugh vaj wIHIvlu'pu'}

(I didn't invent the original sentence, I read a sentence like it
somewhere and understood it, but its grammar bothered me a bit so I
replaced the words to form a grammatically equivalent sentence, for
the purposes of discussing it.)

--
De'vID