had become, had gotten
あいつ、英語がちょっと上手くなってた。
That guy had gotten a little better at English.
本当に感謝ですこの人がいなきゃどうなってたか感謝します
I'm truly grateful. I don't know what would have happened without this person. Thank you.
— タクシー運転手 約束は海を越えて (2017)
お互いに独身ならどうなってたか考えたことは？
Have you ever wondered what would have happened if we were both single?
— 花様年華 (2000)