While the headlight relay circuit sounds like it works as designed, may I suggest rerouting the wires that have added to the positive battery post over to the fuse box?
It's not a concours thing. It's just better practice, if possible, not to hang accessory circuits directly off the battery. That's what the fuse box is for. Look for unused fuse positions (sunroof, power windows, rear wiper, etc.), then the appropriate fuse. It will look cleaner with a more "professional" appearance, and with an archived sketch of the circuit, makes it easier for the next person (or tech) to diagnose. YMMV.
Not worst-case, but typical of too many DIY projects:
The Boy Scout mantra, "Leave no trace behind" applies, especially with electrical mods.
Sherwood