できてた

was ready, was set, was well done, was made well, was able to

→ 出来る
でき can; be able to + て Te-form (conjunctive form) + た Past tense
verb · informal, past tense Rare #32,991
was ready, was set A casual contraction of できていた.
JA: 出かける準備はできてた。
EN: I was ready to go out.
was well done, was made well A casual contraction of できていた.
JA: この料理はよくできてた。
EN: This dish was made really well.
was able to, could A casual contraction of できていた.
JA: 昨日は一人で宿題ができてた。
EN: I was able to do my homework by myself yesterday.
Conjugation of 出来る

私、あなたの名前正しく発音できてた?

Was I pronouncing your name correctly?

私も準備ができてたよ。

I was ready too.

よくできてたよ。

You did a great job.

準備はできてた?

Were you ready?

用意はできてた?

Were you ready?

とてもよくできてたのにどうする?

It was going so well—what are we going to do?

— ほんとうのピノッキオ (2019)