I just did a search on three search engines (cave diving current changes) what I found had to do with the direction of water flow and not the hazard that I described (which makes my point). I know that most people (myself included) often try to 'make their case' in a discussion. However in this one, I believe that you are missing the bus.
My example was an illustration of one hazard, in one specific area. I could start listing hundreds of other examples that are likely unknown to anyone without a similar experience (everyone doesn't write a book). How could you know about these? What are the words that you would type into the search engine? That's why the term "you don't know, what you don't know" is often appropriate.
Once you have a good base of skill and knowledge (someone you trust should tell you when your there, or perhaps you already are?), get a Mentor/Instructor and dive. Increase your experience and you'll be surprised what you don't know. I'm continually learning (mainly through experience) and I've done this for a living for the past 40 years.
You and Bob seem to both reading the same thing with my posts. You both are taking specifics and focusing on one aspect that I mention rather than using the generic "this could happen". Of course you can't know every possible permutation of scenarios by researching online. My point was that your statement and Bob's statement below yours about current changes at a specific site, are now known. No, you might not know the exact time of current shifts, but it's a known fact that it happens at both of the locations you two have used and it can then be planned for and considered in the risk assessment. "Having the chops to deal with it" as Bob suggests isn't the same as knowing you should expect something. As I've stated several times that's practical experience, not planning.
At this point I will stop trying to explain the difference of what I'm saying and what others seem to be getting from what I'm saying. Obviously we have a mis-communication.