Breakdown of Hakkında şikâyet ettiğimiz çevirmen kaynakçayı da unuttu.
unutmak
to forget
de
too, also (de/da) / even if (concessive particle after conditional) / and (linking clauses)
şikâyet etmek
to complain
hakkında
about, concerning
Questions & Answers about Hakkında şikâyet ettiğimiz çevirmen kaynakçayı da unuttu.
How does hakkında şikâyet ettiğimiz çevirmen translate to "the translator about whom we complained"?
In Turkish, to make a relative clause with a postposition like "about," we use the possessed form of the postposition (hakkında, meaning "about him/her") followed by the verb with the -dIk participle. The verb takes a possessive ending to show who is doing the action (-imiz for "we"). So, hakkında şikâyet ettiğimiz literally acts as "our-complaining-about-him/her," which then modifies the head noun çevirmen (translator).
Shouldn't it be onun hakkında since we are talking about the translator?
You could say onun hakkında, but the pronoun onun is usually dropped because the 3rd person possessive suffix inside hakkında (hak-k-ı-n-da) already tells us we mean "about him/her." Turkish prefers to keep relative clauses concise, so the dummy pronoun is naturally left out.
Why do we use ettiğimiz instead of eden?
We use the -dIk participle (here, ettiğimiz) because the head noun (çevirmen) is the object of our postposition, not the subject of the relative clause. "We" are the ones doing the complaining. If the translator were the one complaining, we would use the subject participle -An: şikâyet eden çevirmen (the translator who complained).
What is the purpose of the circumflex (^) over the 'a' in şikâyet?