To type the word Mangaí correctly with tonal marks:

The font is a popular Unicode-based font used for the Meetei Mayek (Manipuri) script. Because it follows the Unicode standard, the text you type is standard Meetei Mayek.

MCL (Mangai Computing Lab) provides the layout without cost, often bundled with font packages. No nagging trials or spyware.

Here is the proper text mapping and keyboard layout guide for the MCL Mangai font.