This is my favorite thing I've gotten to share here so far. It's a ROM dump of a prototype copy of A-Force by Sachen I found a few months back. Technically this is the Mega Duck version, but Mega Duck games are mostly the same as Gameboy games at a programming level. I shipped it out to Sean Riddle who was able to dump it (he redumped a few times to make sure it is a good dump) and gave me some info on his findings:

"The EPROM is connected directly to the cart data bus D0-D7 and the cart address bus A0-A14.  Chip enable is connected to cart A15, so the EPROM outputs are tri-stated for addresses $8000-$FFFF.  Output enable is connected to /RD.  EPROM A15 is connected to the MC14174B HEX Type D Flip Flop’s output 0.  The flip flop’s input 0 is connected to data bus D0, and the clock input is tied low and connected via a diode OR gate to /WR and A14.  So writes with A14 low will latch data bit 0 for use as EPROM A15.  The flip flop’s /reset signal is connected to the cart’s /RST pad so that the game starts up in bank 0.  The other 5 flip flops are unused.

This 32K bank switching is different from the 16K bank switching used in the production carts.  That likely explains why large blocks of code have been shuffled around."

Interestingly the shell for the cart appears to use the design for Mega Duck carts that is seen in old advertisements (light colored plastic and slants on the sides of the cart)

I don't think it is. The description I heard for Blood of Jurassic is that it has the same Shanghai Paradise crest that Super Hang On has, as well as the ID code GD-98 on the sticker

Do you know who can fix these?

I currently do not have any contacts that can help you. Sorry

To answer your question on whether or not unofficial Taiwanese Famicom games were sold in Europe, the answer is yes. Some was even sold in Western Europe and Canada. I would say those are not good locations to search through though. Not because the carts aren't there, but because you're going to mostly see official carts, so you'll be sifting through a bunch of stuff you don't want. Since you have a pretty short list of things you are looking for I would recommend taking your time when it comes to searching so you don't wind up overpaying a ton or get stuck using expensive shopping agents

It's undumped. Also, why mix Chinese and English for the name of the game? Shouldn't it be Pi Ka Qiu Yong Chuang Emo Dao if you use toneless pinyin?

Chinese version of the Makon fighting game. UCM: Makon New

Original SL release of Devil Land by Vast Fame. Use UCM for Vast Fame's SL releases in hhugboy

Dark alleyway sales would be a pretty bad business model for this sort of stuff. Most of this stuff could just be sold out in the open since it was in countries where IP law was either weakly enforced or not enforced

Small shops I would guess was the most common distribution method, followed by mail order.

Where and when you were buying this stuff matters though. Waixing had (or I guess has) a very long career and was in Mainland China. I've heard Chinese users mention their games being available even in larger stores (supermarkets) at one point, but Waixing continued operations in the Famicom business much later than Hummer (which stuck around for a while but had moved on from cartridges). Out in Taiwan though it was only really small stores since this stuff died out earlier there and larger stores weren't much of a thing back then there

Without statements from people who were there though it is hard to say for certain for each game. Sometimes they showed up in magazine ads if you were lucky