So how does someone need to go about flying in a different country today "legally"?
Exactly as you might expect; you read-up the requirements for flying in that country, make sure that they have actually implemented the new regulations, and comply with any test/registration/license number display requirements, payment of fees, etc.. And, yes, that often means all the hassle and inconvenience that goes with using tools like Google Translate on technical speak, which can be a huge PITA on some occassions. Some countries *do* offer a simple waiver for tourists, albeit often with things like no commercial usage, no night time flying, and strict VLOS restrictions, so if that's all that you intend to do then it might be possible to skip the test requirement.
English *is* the language of International Aviation though, so if you get stuck then reaching out to the national Aviation Authority in English will usually get a response and at least some assistance - demonstrably trying to do the right thing does seem to be appreciated. I've flown in quite a few countries now, and generally provide as much detail as I can up front - UK CAA registration info, type and weight of drone, where I am intending to operate, what kinds of images and be shooting and why, and *always* show that I have knowledge of local laws. I then run that through Google Translate to put it into the local language and include that too. Initial responses can be mixed, and have ranged from permits being sent in the reply (on a few occasions negating the need to do a test!) to not much help at all other than links I'd already found, but so far I've been able to sort out something for every country I've wanted to fly in where permits are required, albeit with a little perseverance required sometimes.