First, we recommend reaching out to the App's support contact. You can find this contact on the right side of the App's Page. For example, here is Chatra's Page.
Another contact to share your feedback and see if other's have had similar ideas/issues is the Cloudflare community site for Apps.
If the app you'd like to see modifications for is built by Cloudflare Labs, the source code is on Github here. We would be happy to review and accept pull requests.