It would be better if you switched it around and changed ‘Beau’ with ‘Bo’, so Lilah-Bo if you want to use that name.
2 of my children have names that are usually used by males but I have come across 2 girls called the same, it was a little odd purely because I’m so used to associating the name with a boy but the names do work for girls.
Beau is not one of those names that’s interchangeable as it’s a masculine version of the name Belle, so you could do Lilah-Belle then when she’s older she could pick which name to choose, Lilah-Belle I think is pretty for a hyphenated name.