> One frustrating thing here is that this adapter was never designed to be used with loose cartridges, but only PCBs. Famicom cartridges are a nightmare to open without damaging them due to reinforced plastic snap tabs, so people who wanted to use these as adapters would just take a rotary tool to it, as this blog post from 2006 shows.

You can plug a Famicom cartridge into the Nintendo converter by pulling off the gender adapter and plugging it in the other way so the tabs that block the cartridge are on the bottom. Note that it's tricky to remove the converter from a front-loading NES, which is why most aftermarket Famicom-NES converters have a ribbon to help with pulling them out of the system.

> NES and Famicom cartridges

They are Game Paks and cassettes, respectively. Of course it's obvious what the author is referring to, but I really enjoy seeing the term “cassette” used for something that doesn't contain magnetic tape, so please pardon my pedantry :)

Peep the Famicom system manual where the cartridge connector is straight-up labeled in English as 「ＣＡＳＳＥＴＴＥ ＣＯＮＮＥＣＴＯＲ」with katakana furigana (カセット / kasetto): https://ia601903.us.archive.org/17/items/Family_Computer_198...