During his long discourse, he did not touch that point.

• Correct Sentence - During his long discourse, he did not touch on/upon that point.

• Touch on/upon something (phrasal verb):
English Meaning - To mention a subject quickly when speaking or writing about another subject.
Bangla Meaning - (কোনো বিষয়ে) সংক্ষেপে আলোকপাত করা।

Example Sentences:
- The talk was about educational opportunities for adults, and the speaker also touched upon sources of finance.
- Before concluding, I would like to touch on the excellent work done by our interns.

Source: Cambridge Dictionary.