The localization project I use as an example here was definitely one of my top 3 hardest projects of all time (and that was years ago). It was not a particularly difficult technical challenge, it was difficult because it touched every single aspect of the codebase. The project took me and a coworker 3 months to build out the infrastructure for, then another 3 months of actually rewriting everything to use it, and explaining to every single other developer about why we made the decisions we made in order to teach them the different ways they were going to have to write code from now on. Social challenges of the workplace are hard; we're not always looking for technical difficulty.
Off topic but: this is some good nostalgia here. I was that other coworker. Some of the best pair programming I've ever done. It was fun working closely with Nick.
It's definitely hard. There was certainly no clear cut solution to any of the problems I included on the card in the picture. We evaluated 8 or 10 different solutions for out of the box stuff, found things we liked and didn't like about all of them and eventually decided it was best to build our own. At each step there was a lot of debate because we knew this would probably be used beyond just the Careers project and be used in the Q&A project as well (separate at the time), so it wasn't just worrying about my team's concerns, but everyone's. We won some debates, we lost some debates, it was very hard.
I've done localization conversion projects a few times so I can relate. There's never one way to translate everything (e.g. page content, URLs, database content, images, forms), there's usually several translation methods to evaluate, you have to trawl your whole codebase to tag text for translation, translating routes/URLs tends to break all code that doesn't expect those names to change, new developers have to be taught to develop new content with translations in mind, you have to schedule allowing content to be translated along with time to get it translated to get everything done on time and you need a new workflow for how translatable text is delivered, translated, reviewed and deployed.
