I think you've touched on two different ideas: (1) That a deeper understanding of something can make it simpler/easier to remember. One way to look at this is

I think you've touched on two different ideas: (1) That a deeper understanding of something can make it simpler/easier to remember. One way to look at this is that you remember a model of the world. That complexity of that model determines the quantity of information you need to remember. If you can find a simpler model, your mind needs to store less information to cover everything you need to know. (2) That a concept and its name are different things. You understand the concept of an array-length-giving function, but you don't remember the name attached to it. It could go the other way: you could know there is a function with a certain name but not remember what it does. Or you could know what it does and what it's named. (This seems at least tangentially related to linguistic relativity (https://en.wikipedia.org/wiki/Linguistic_relativity https://en.wikipedia.org/wiki/Linguistic_relativity), a.k.a. the Sapir-Whorf hypothesis. The question is basically to what degree our minds build ideas on words/language and to what degree we form ideas independently of language.)