Yeah, don't get me wrong. As a non-native speaker I can't feel this linguistic finesse. Up until only a few years ago I hadn't seen the term "custom" used for basically stock prebuilts with switches or caps replaced. So, for me at least, "customs" remain these weird designs which many people would have a hard time to identify as keyboards.
(On the other hand, I always thought "bespoke" and "custom" are synonyms.)