I wanted to double check if I understand the mistakes in your examples.
bondlingo.tv/blog/the-polite-three-teineigo-keigo <- 「彼女は可愛いだ。Kanojo wa kawaii da.」「今日暑いだ。Kyou atsui da.」!? bondlingo.tv/blog/learning-the-japanese-keigo-sonkeigo <- 「私は明日までお待ちになります。Watashi wa ashita made omachi ni narimasu. I will wait until tomorrow.」!? 「雨が振りそうです」って、漢字も間違ってるし。そのサイト、信用しないほうがいいと思います
In the first two, the mistake was that だ was added at the end, which shouldn't be done after an adjective, right? And what was the mistake in "私は明日までお待ちになります"?