I've traded extensively from Taiwan, Philippines, Vietnam, and briefly from Hong Kong.
The only place I had trouble was Philippines, throughout 2017. Even with the best connection, it was spotty. I don't know if it's improved in 2018.
Internet in Taipei, TW (whether from your cellphone hotspot, a locally paid wifi connection, or even the free public wifi in train stations) is extremely fast, and I've never had a single hiccup using any of them. (Have traded with them all.)
Internet in Ho Chi Minh city, VN is fine for trading. But, it's possible that it goes down abruptly from time to time. I've never experienced one of these outages myself, but I've heard from local friends that it's attributed to "sharks eating the cables". Not sure what to make of this response...
https://www.independent.co.uk/life-...e-eating-the-internet-in-vietnam-9962747.html
HK was fine, but I was only there briefly. I'm thinking a lot of traders there. It's a financial hub.
As for other parts of East Asia (Japan, Korea, Macau, China), I doubt you'll have any trouble trading in world class cities like Seoul or Tokyo.
For South East Asia, I have friends who trade from Thailand with no problems. Lots of "digital nomad" types live there in Chiang Mai and also Bangkok.
I'm guessing Singapore you'll be fine.
Safety throughout East Asia is not a major concern. SE Asia on the other hand, may be dangerous if you veer too far off the beaten path of other foreigners.
Never traveled in Europe so that ends my contribution.
Enjoy your trip.
BTW-- How did you become fluent in Mandarin and Cantonese? Those languages are both complex and not mutually intelligible. If you can freely converse in both (and English), that is quite remarkable. I envy you.