Differences in verb-subject-object word order will always add latency. If you want to translate from German, with the verb at the end, to Welsh, where the verb goes at the start, you'll have to wait for the complete sentence before you can begin.
Not necessarily true, for the first few sentences you won’t be able to do it. But afterwards, once the context is established you don’t really need to wait for the verb, you can predict it. For example if you are speaking about cleaning the house and you detail that you have cleaned the kitchen the stove and so on, you can predict the verb with only the start of the sentence. I don’t have any source to back this up, but it sounds plausible
A good approach might be to start with how top notch, ultra-experienced human translators handle corrections for real-time scenarios, for example, the expert translators that do the ear monitors at the United Nations. I've worked with a few such real-time translators when preparing keynote speeches and they seem to have rigorous processes that appeared quite deep. Probably a ton of domain expertise to be captured there.
That said, I suspect that real-time language translation is always going to be somewhat imperfect due to its nature. Non-real-time translation of literature is still a subjective art form even at the very high-end of human expertise.
Although true and considering what “mrob” had also replied, this will never mean full translation every time, all the time. This will work with specific environments and linguistic expectations.
I’ve been learning german since 8 years, and the amount of expressions and different ways to say things around the country is impressive. There’ll be a “interpretative” real-time translation, but it won’t guarantee fully understanding in so many cases, maybe ever.
Other thing, and we have this in common with all languages, is the context and this is difficult to address i believe.
Nevertheless, it’s impressive how far we’ve reached and i acknowledge the usability of these tools. However, human knowledge will be always crucial and primordial if we want to guarantee full understanding.