How can I find an app on my iPhone?
If you have Open_Term or another app that you can use the command line on, go to that app and cd into your directory. Then type ls -laRt. That will list all the contents of all the folders. You can then search the output for the app you want.

It's a lot to do for what you want. There should be an easy and automatic way to do this.

You can also use the spotlight search which should give you the folder the app is in. From your home screen slide the desktop to the right to get the window where the widgets are are accessible. At the top of that window is a search bar. This is the spotlight search. Type the complete name of the app in the search box and hit return. If there is only one match it will list the folder where the app is stored.