I've heard lots of speakers use "hopefully" at the end of their lectures.
Consider this example
We have learned that Britain’s weather is very changeable and hopefully we have learned how to describe the weather in more detail using phrases and expressions. Thanks very much for watching!
where "hopefully" is used to describe "have learned ...", which does not make any sense.
"learn" is an action, which had already happened before the speaker say that.
Cambridge Dictionary gives these definitions about "hopefully"
used, often at the start of a sentence, to express what you would like to happen
in a hopeful way
why does the speakers express they would like the action of learning to happen after the action had happened?