I have VJJB K4S (and BK50).
The K4 is eye candy for sure. Absolutely beautiful wood and metal construction. The sound is v-shape, and it’s overall it’s a decent ChiFi IEM. A little dated compared to the stuff available nowadays, and I would rate it average overall. Easy to drive, comfy to wear, nice punchy bass, smooth highs. Overall very fun sounding and not fatiguing at all. There’s better stuff, but certainly worse stuff.
The Tennmak Pro is kinda meh. A little too dark and boated, with not enough clarity for my tastes. I like the Tennmak Crazy Cello way better.
The T2 is excellent, and does actually have plenty of bass. It requires a deep insertion, which most people do not do. This can be achieved by wearing it up not down, swapping the L and R shells (allowing it to tuck into the ear deeper). When worn down, the insertion is shallow because it hits part of the ear (for me anyways), and I think this is why it has the reputation for light bass. The shape of the shell is not very ergonomic, which is really unfortunate because it has amazing sound.
So since you asked about the Magaosi BK50 and VJJB, I assume you’re looking for a wooden IEM?