Ananda
The Bunker Group
Actually there're several Naval "consultants" that can be used by Taiwan on helping them for this Submarine projects. That's from what can be seen are some of the way Taiwanese uses on getting foreign suppliers help for their domestic industry defense tech.but still its unclear from where the Taiwanese get their expertise/ToT to build new submarines from.
Direct co-op with Taiwanese Domestic Defense Industry off course will get risk on Chinese market closure. However using 'third' parties as indirect tech provider can work around that. Look at their indigenous light fighter, in my opinion it clearly shown Northrop influence. However no official Northrop co-op when Taiwan developed that.
Taiwan according some media already prepared their indigenous Submarine projects perhaps since early 2000, when it's clear to them Netherlands Ship Yard did not want to help them getting Walrus based Submarine.
Taiwan shipyard tech also quite advance in capabilities. When you have budget to do it there's way to get around trade embargo (in this case China). After all if Iran with much less cash reserve can circumstances US embargo in developing their own submarine design, then Taiwan (which still has de facto US support) certainly can also find away to circumstances China.