I can’t see what the problem might be in switching the negative?
An H4 incandescent lamp has two filaments, one for high beam, the other for low beam - and three terminals - high beam, low beam & common
The H4 version of the lamp will contain two diode arrays, one for high beam, the other for low beam, and the same three terminals, so either the anodes will have to be connected together and the cathodes separate, or the cathodes connected together and the anodes separate.
In a conventional automotive environment, for example the park/side lights on a Jimny, the positive supply side is switched, and the negative side is connected to the chassis.
On many cars, the headlights are conventionally switched, so that common terminal in the bulb is grounded and the positive supply switched to the high beam or low beam terminal as required - on a Jimny, and every other Suzuki I've looked at, the headlights have been negative switched, with the positive supply connected to the common terminal in the bulb, and a ground applied to the high beam or low beam terminal.
Because diodes (LEDs included) are polarity sensitive, not all LED lamps work in a negative switched headlight system,
By the way, over current is what kills LEDs - over current & over heating. My first exposure to LEDs was in the late 70's when red was the only color available, and all they were good for was panel indicators and seven segment calculator displays.
