Correct my sentences, please.

Correct my sentences, please.

Yes, I’m very strict. But he is also very strict with himself.> ok

> Yes, I'm very strict , but he is very strict with himself too > I joined then because they are related.

Even though I said “That’s right” about his pronunciation of a word he was struggling with pronouncing with correct accent, he didn’t finish pronouncing it.  x

> Even though I said that his pronunciation of a word that he had difficulty pronouning correctly (earlier) was correct , he kept on pronuncing it .

> Even though I said "That's right" in response to his question about the correctness of his pronunciation of a word that he was struggling to pronunce correctly , he kept on pronuncing it .

> Correct way , not accent . Accent is normally acquired over time . I speak English well , but I dont have the English accent . I dont need that anyway .

He repeated pronouncing it more several times until he convinced.

> He pronouned it repeatedly several more times untill he was satisfied

> He pronounced it repeatedly several times more until he was convinced that he had done it correctly .

However/But he made a mistake again.

So, he had to restart the whole exercise again to learn to pronounce the word correctly

(pronouncing it with correct accent).

So , it took about twenty minutes just to teach him one word yesterday.

I think that his enthusiasm/eagerness will surely bear fruit.

I expect that the day he speaks Japanese with a standard accent like a native speaker born and raised in Tokyo will come.

I look forward to the day when he speaks Japanese as fluently as native speakers (who are raised and born in Tokyo) ,and the day  will surely come .

I expect the day when he speaks Japanese as fluently as Japanese themselves to come sooner than later.

You use "expect" > I have to elaborate your sentence

そう、私はとても厳しい。しかし彼も自分自身にとても厳しい。彼が正しいアクセントで発音することがなかなかできなかった語句を私が「それで正しい。」と言っても、彼はそれでその発音をやめることはなかった。自分が納得するまで更に繰り返した。その結果再び間違って私からの注意を受け、その後語句の発音練習を再開することとなった。それで昨日は或る語に20分ほど費やした。私は彼の熱心さはきっと実を結ぶと思う。私は彼が東京育ちの日本人のように標準アクセントで日本語をしゃべる日が来るのを楽しみにしている。