If you search for your question via Google like this - 'Compute Canada memory per core' you'll be directed to the glossary of terms for Compute Canada. On that page they define it like this:
Memory per core: The amount of memory (RAM) per CPU core. If a compute node has 2 CPUs, each having 6 cores and 24GB (gigabytes) of installed RAM, then this compute node will have 2GB of memory per core.
Memory per node: The total amount of installed RAM in a compute node.
I'd also direct you to this page titled: Allocations and resource scheduling. They cover in excruciating detail how they handle the billing/scheduling of jobs that are RAM vs. core heavy.
A core equivalent is a bundle made up of a single core and some amount of associated memory. In other words, a core equivalent is a core plus the amount of memory considered to be associated with each core on a given system.
Cedar and Graham are considered to provide 4GB per core, since this corresponds to the most common node type in those clusters, making a core equivalent on these systems a core-memory bundle of 4GB per core. Niagara is considered to provide 4.8GB of memory per core, make a core equivalent on it a core-memory bundle of 4.8GB per core. Jobs are charged in terms of core equivalent usage at the rate of 4 or 4.8 GB per core, as explained above. See Figure 1.
So I do not believe this has anything to do with NUMA in the traditional sense. It's more the case that the Canada cluster management group has arbitrarily decided what a "core equivalent" is with respect to the different compute clusters they provide.
Their Graham + Cedar clusters provide 4GB/core, whereas Niagara provides 4.8GB/core.
The concept would appear to be completely a logical segmentation at the job/scheduling level of their compute cluster.