Student or Learner
All can you please help review the below sentences.
"He confirmed that for previous release, test team used open source software. But he is not sure if the tester checked the version of open source software. He also mentioned that test team discussed this with development, and since there is no product requirement they agreed to use open source software going forward"
In the above sentence, confirmed is in past tense and "but he is not sure" is in present sentence. Is this correct. Instead of "he is" should it be "He wasn't sure" ? Is there any other grammatical mistake in the above sentences ?
Thanks for your help.