Taking a look at some examples of the phrases "within the backend" and "around the backend" on Google Books, it seems that everything that runs in the backend (processes, services, etcetera. In several cases, absolutely the path for each of the prepositions may be effortlessly inferred from the context, e.g. https://web-design-in-south-flori80123.tinyblogging.com/frontend-development-services-in-usa-an-overview-80133464