it works, but there are issues when using symbols (such as “!”, “,”) or accented words (e.g. “olá” = hi in ptbr)
it would be better to have the text field exposed to be set, instead of having to guess the url and try what would work. just spent amost 50 out of the 200 views from the free plan in order to try and test.
Hi there and welcome to the Community 
I’ve shared your request with our devs and will let you know once I receive a response form them 
Thank you for waiting!
These symbols are not supported in a prefilled message due to the peculiarities of the link validation. I am really sorry!
As you’ve suggested, this issue can be resolved with adding a separate field for setting the prefilled message right in the configurator. Glad to tell you that we are working on this feature at the moment.
I’ll keep you informed about any progress here