Translation:I think that it is better for us to wait another thirty minutes.
"more than" is "mais (do) que"
- Mais trinta minutos = thirty more minutes
- Mais que trinta minutos = more than thirty minutes
" I think it is better if we wait another thirty minutes." is marked as wrong. I have reported it. Am I right?
Maybe it is about the word "THAT" that you had left out of your translation? .
I don't like using "if" here. That is "melhor se esperarmos"
The best translation, I think is: "it's better for us to wait"