Maybe take a look at the certification requirements? That should help you decide on how you should study.
That aside… you’re probably going to want to get really good at Japanese first. After that, the next step (for translating) will be knowing how to match nuances across languages. Of course, a good English-Japanese dictionary will probably be really helpful, especially one with example sentences, but those will only take you so far: when you have a refined understanding of nuance in English language, sometimes, you’ll look at all the translations in the dictionary and go, ‘OK, no, none of these really fit. We’re almost there, but that’s not quite it.’ That’s when your ability to translate really gets tested. You’ll probably find that you have more freedom translating between English and Japanese than, say, translating between English and French (because those two languages are much closer structurally and in terms of vocabulary), but I guess you should always ask yourself, ‘Is this really what the sentence means?’ If you’re like me, you might go one step further (but this is just a matter of preference): ‘Does this really capture what the author intended and replicate the feel of the original Japanese sentence?’
As far as ‘getting good at Japanese’ goes… I’ve never gone for a university Japanese course before (I’ll be trying one later this year in my engineering course if all goes according to plan), but as many people have said, they tend to be slow. Just to give you some perspective: in France, even a student at a specialised institute in Paris studying Japanese culture and civilisation is only recommended to take the JLPT N2 after three years, with the N1 being recommended for students with a ‘good level of Japanese’. In comparison, I think some of the fastest people on these forums reached N2 (at least in reading) within about a year. Sure, perhaps those people are faster than average, but the point is that university language courses tend to take their time and may slow you down if you’re capable of learning faster than that. I think a language school is probably a better choice insofar as they’ll probably be more language-intensive (and hopefully spend less time on useless technicalities), but again, it could slow you down if you’re a diligent, motivated self-learner. Personally, I’d recommend self-learning, or at least checking out popular beginners’ textbooks and then picking a school that uses the ones you like. Otherwise though…
This would be roughly my game plan if I were you. Caveat: I’m a Chinese speaker, so I don’t use any kanji learning apps, including WK, and I don’t find picking up new kanji too hard, though I’ve had to invent/absorb a few new ideas to memorise ones with lots of strokes (that are probably basically useless anyway, like 釁る and 灋, which is the old version of 法). I replaced Genki I & II with Assimil’s Japanese with Ease, which might be out of print in English now (or only available second-hand): skimpier explanations for grammar, but good enough for me, and probably more kanji and advanced words than Genki by the end. As for native content… yes, reading is good, but if that doesn’t motivate you too much, you can replace it with other native content that you’re willing to study: for me, I watched tons and tons of anime and looked for the transcriptions on Anicobin (it’s a reaction blog with screenshots), and then looked up the words I didn’t know/found intriguing. It’s also a good way to learn grammar. Japanese songs can also be studied like that. The benefit of using something that you like is that the words will stick as sound bites or short phrases in your head.
Also, just IMO, when you get to the more advanced levels (think upper intermediate/nearing N1), if you’re having a hard time breaking through the plateau and finding material that will teach you more new words fast, then try these textbooks on top of native content:
I’ve got the 中・上級 book. I haven’t looked beyond the first chapter yet, but suffice to say that every single sentence of the first chapter passage has about three words/phrases in it that I don’t know. That’s productive study time. Even newspaper articles don’t usually challenge me that much.
Either way, all the best, and I hope you find a language school you like.