There's no need for others to know it if they don't know it unless they want to apply it to their lives and try it. There's no need for them to adopt the surroundings IMO and that's how they get used to what they do and as well as get used to the surrounding that they're living with.
It's all about what they used to do and believe and so the others too, that's how they're going to live and deal with the others as well.
At the very least, they must be able to adapt to their environment before they can adjust to their wishes. If they don't, I'm afraid there will be unwanted friction and it could end up causing something bad for everyone. If they can follow well, I'm sure nothing will happen and everything around them can also get better so that the environment will slowly change into a good situation. We don't want anything bad to happen either, right?
I don't see that there will be some effect for others that it will be bad for them. It's just a belief and if anything goes wrong, it's to those that have that belief and they'll just move on afterward.
Whether you don't wish them misfortune or whatnot, there's really nothing you can do with such decisions being applied by them for these beliefs that they've got like feng shui.
I don't want them to be unlucky or bad or anything because they are part of the community that lives around us. So it would be better if we could respect their beliefs and not interfere with each other in their affairs because we don't know exactly what and how. We can let them keep practicing feng shui if they still want to use it because it is everyone's freedom to do what they want.