EDIT: It appears that variants (or block files entirely) are not loaded properly to accept changes by resource packs. This includes changing rotation values or specifying different models, the game will still use the default values. However, these files DO seem to load, and cause the game to crash upon initialization if there are values it doesn't like.

Example:

I use coordinates from images in GIMP to create models, in a front-facing perspective, with X being width and Z being depth. I was able to convert my ladder file from the older format, and the only issue is that Z was inverted.

So I get to converting my torches. These for some reason are rotated 90 degrees, and editing the block file to change the rotation doesn't work. Even setting them to not rotate has no effect:

{
    "__comment": "Fair warning, this format is highly likely to change even more in the future!",
    "variants": {
        "standing":  { "model": "torch" },
        "wall_n":  { "model": "torch"},
        "wall_s":  { "model": "torch_wall"},
        "wall_e":  { "model": "torch_wall"},
        "wall_w":  { "model": "torch_wall"}
    }
}

However, the file seems to be parsed, because if I set one of the rotation values to 45, the game will crash. So, short of redoing the model, I can't fix the rotation.

A hotfix for this is to rename the torch_wall.json file something else, and then make a new torch_wall.json with this code:

{
    "__comment": "Fair warning, this format is highly likely to change even more in the future!",
    "inheritFrom": "torch_wall2",
    "rotationOrigin": [ 8, 8, 8 ],
    "rotation": [ 0, -90, 0]
}

The torch model file wouldn't allow me to use a different mesh file, but this way works.