Q.Echeveria Care
I have used lemon juice to clean water marks off my echeveria plants and I’m worried that I have damaged them by removing the protective coating. Can I rectify this?

On what basis are you worried - do your leaves look damaged or sick? Echeveria leaves are covered in a waxy powder that helps protect them from sunburn. It can be wiped off pretty easily which will make the leaves look discolored, which is probably what raised a red flag. This waxy coating will be restored over time.
For more information on echeveria, please visit the following link:
https://www.gardeningknowhow.com/ornamental/cacti-succulents/echeveria/caring-for-echeveria-plants.htm