Overall, the flannels/tartans are pretty neat.
I may not be as well-versed in fashion and cultural history but I think Episode had good intentions in releasing some items which are associated with prior plaid clothing. They are a company based in California, US, of course they would portray ‘diverse’ fashions, albeit in a limited point of view. Everyone to some extent cannot be aware of every cultural contribution in the world, coming from a Chinese Singaporean.
Tartan has an impeccable history both in Europe and the US, expressing rebellion and national pride especially in the former. Here are some articles I found which seems interesting:
That being said, more traditional Scottish clothing as well as lesser-known yet prominent European/Asian ones would be appreciated. Literally the other ‘Scottish’ item of clothing I can think of from Episode is the Ink ‘Touch of Scotland’.