How do I make this work? Request for help from Brazil

I created a keyboard app but I can’t get a character to work in the longpress popup.
I added the character “á̱” but I don’t know what to put in the box of keys or in the code, because the character is the combination of “á” (U_00E1) and " ̱ " (U_0331).I tried to recreate the character as a single piece using the windows private character editor, so I can use a unique key but when I choose the character in the app only a Japanese character appears. How do I make this work?