Launch app in foreground doesn't work from cron, but does from terminal
For me on macOS High Sierra, e.g.:

 * * * * * open -a TextWrangler ~/notes.txt; open -a Notes


works as is, both apps come to the front.

Try adding, e.g.:

; osascript -e 'tell app "TextWrangler" to activate' -e 'tell app "Notes" to activate'


to the end of your existing command and see if that makes any difference, e.g.:

* * * * * open -a TextWrangler ~/notes.txt; open -a Notes; osascript -e 'tell app "TextWrangler" to activate' -e 'tell app "Notes" to activate'