I absolutely agree with your analogy.
Please consult the manufacturer of the accessory you wish to modify. Unfortunately, this is not the same as the manufacturer of your car. Next time, choose genuine accessories.
Not sure how else to explain this…
As for how complex it is, it’s all in your head. I don’t find it complex to edit my theme files, but you’re here posting this, so evidently you do… this is a matter of perspective.
Ultimately, the files are all there. The way things look is a function of the theme you downloaded, if you want to change that, then consult the theme’s user manual. If it doesn’t have one, then direct your complaints to the author of the theme.
… or save your energy and start poking around in the files.
I still feel it’s important to have some basic concepts available to you, before you begin pouring coolant where your power steering fluid should go. The internet is full of information on both auto repair, and web design if self-help is the path you choose ??
Just trying to put you in the right frame of mind… because constructive crticism is only constructive when directed at the appropriate target.
in the mean time, check the style.css in your theme folder for the sidebar value you should be changing. Having no direct experience with this particular 3rd party accessory to your wordpress installation, I can only make an educated guess about that.
Good luck.