If it had been initially called Indo-Celtic or Indo-Romance and those names had stuck, it would be equally fine, but that's not what happened historically. You

If it had been initially called Indo-Celtic or Indo-Romance and those names had stuck, it would be equally fine, but that's not what happened historically. You're fighting against windmills, there are no perfect names for huge language families, this gets even worse when we look at certain language families in other continents. It's very common to just pick two subbranches (or geographic regions), combine them and call it a day (e.g. Sino-Tibetan).