You can try to add the resources in the asset block of theme.json, as suggested in the error message.
Something like the snippet below
{
"lumoImports": ["typography", "color", "spacing", "badge", "utility"],
"assets": {
"line-awesome": {
"dist/line-awesome/css/**": "line-awesome/dist/line-awesome/css",
"dist/line-awesome/fonts/**": "line-awesome/dist/line-awesome/fonts"
}
}
}