In my experience, you just need to load the normal one and the bold and oblique will work fine.

@font-face {
	font-family: "Computer Modern";
	src: url('https://localhost/matesvolta/wp-includes/fonts/latex/cmunrm.woff');
}
@font-face {
	font-family: "Computer Modern";
	src: url('https://localhost/matesvolta/wp-includes/fonts/latex/cmunti.woff');
	font-style: italic;
}
@font-face {
	font-family: "Computer Modern";
	src: url('https://localhost/matesvolta/wp-includes/fonts/latex/cmunbx.woff');
	font-weight: bold;
}
@font-face {
	font-family: "Computer Modern";
	src: url('https://localhost/matesvolta/wp-includes/fonts/latex/cmunbi.woff');
	font-weight: bold;
	font-style: italic;
}