Will Slope Ratings be updated?

So if course B has a CR of 71.5 compared to our 69.9, does that mean it's rated harder than ours for scratch golfers, but easier for high handicappers? That defies logic, unless I'm missing something which is quite possible!

Not quite, because it is all relative.

Take a standardish course. Course X

Then go to Course A. It is an open course, but many of the holes have water around 220-260 yards from the tee. This course is relatively harder than Course X for scratch golfers, because the water is in their landing zone. They will need to lay up, thus eliminating their advantage off the tee. This will give a higher course rating than Course X. But, the water is too far away to bother higher handicappers off the tee, so has a lesser effect. So, the Bogey Rating may be lower at this course than Course X, thus providing a lower Slope.

Then go to Course B. It is an narrow course, and many of the holes have water that require 150-200 yard carry from the tee. The course may be as tough, or a little tougher than Course X (as I didn't define much about that course), so the Course Rating may be roughly the same, a bit higher possibly than Course X. Basically, the water does not really hurt the lower handicappers, as they can drive over it. However, these holes are extremely difficult for the higher handicappers, who will struggle to carry the water on all these holes. So, the Bogey Rating could be much higher than Course X. This would result in a high Slope (remember, the slope is simply a function of the difference between Course and Bogey Rating). So, although the course may not be relatively much more difficult for scratch players, it is relatively more difficult for higher handicappers, compared to Course X.

Just a very basic example. Generally speaking, the relative difficulty between low and high handicappers goes up for longer courses. However, the set up of the course can have a big impact at times. In my experience, I've gone to links courses locally, that are, in absolute terms, very difficult to play. Especially for low handicappers. However, because they are also very open, and wayward players can potentially get away with bad shots, they are not necessarily relatively more difficult for higher handicappers, and therefore the Slope is not as high as some people think it should be (when they mistakenly think Slope reflects absolute difficulty). In effect, although it is still absolutely harder for the high handicapper than the low handicapper (i.e. the high handicapper is not expected to shoot a better gross score than the lower handicapper), the difference between their handicaps will be lower as the slope is lower.

In other nations, like the US, they factor in CR-Par into the course handicap calculation, and so golfers typically see the changes to their handicap that they expect (because their course handicap takes into account both absolute and relative difficulty). In UK that is not the case, so you still need to compare your final score to the Course Rating of the course, not Par.