Contact the seller and ask them. I agree with JoeJr that no one wants to give wrong advice about electricity. I'm in that camp as well.
That said, and for what it's worth, I've worked on 6 and maybe 7 or 8 foot pedals, including rebuilding old style Singer button controllers, and I've swapped wiring to connect them from one machine to another. My experience is that no, it makes no difference which wire is connected to which terminal. None of my pedals had a "ground" wire which in the UK I believe is called an "earth" wire. I don't see a ground on your pictures either. Where a ground is present, it can get somewhat confusing because there are three wires and people often don't know which one goes where.
Using a lamp as an example, if you wire a lamp or a light switch, or an outlet, there will be two different coloured screws, one brass and the other steel. Generally, what you do is wire the "hot" to the brass screw. The "hot" in North America is the narrow blade on the plug and that blade fits into the narrow slot on the outlet. The other way to tell is that the "hot" is the one that goes to the centre of the light bulb. The wire itself is also marked in that one side will be round the other side will be square or otherwise marked. That way you can double check which is the hot and which is the "neutral". So in those cases, you make sure that the wire of your lamp that leads to the narrow blade of the plug, which is the "hot" is screwed to the brass screw of lamp. The reason for that is that if you wire the lamp socket incorrectly you've in effect reversed the polarity and even if you turn off the switch, there will still be power running to the lamp. So if you change the light bulb you risk getting a shock even if the switch is off. If the polarity is correct, when you turn off the light switch the power is completely off and you can change the light bulb safely.
On your pictures, the screws are the same colour and I don't see a ground. So there isn't a "hot" or "neutral" to worry about. These connectors look just like all the ones I've worked on. If it were me, I wouldn't have any concern about which wire is connected to which screw. This circuit doesn't have a switch that turns on and off so there's no issue about polarity potentially causing a problem.
All of that said, contact the seller to ask them if you're unsure. I believe I'm correct in what I've said here, but I'm not an electrician.
A few other bits of advice, always make sure to unplug your sewing machine when not in use. Make sure you tighten the screws good and tight so that there's no change they come loose. If when you touch the sewing machine, or any electrical appliance, a lamp, a microwave, a blender or anything at all, if you feel any kind of vibration, or buzz, or tingling feeling, it may be that you have a small short circuit. Unplug the appliance immediately and get it looked at by a professional.
Last edited by 1.41; 09-12-2022 at 09:26 AM.