There are many ways you can give feedback about JExcel:
About MORESIMP Help Center:
If you go clcik on the Feature request or Bug report, you will be taken to the MORESIMP Help Center where you can:
To do any above, you need to need to create an account to MORESIMP
When you are logged in, you can vote to features here: https://moresimp.atlassian.net/secure/Dashboard.jspa