Difficulty is not additive, and measuring the difficulty of proving a single result is not a good measure of the difficulty of understanding the body of work in a given field as a whole.
Suppose for instance that 100 years ago, there were ten important theorems in (say) complex analysis, each of which took 30 pages of elementary arguments to prove, with not much in common between these separate arguments. (These numbers are totally made up for the purposes of this discussion.) Nowadays, thanks to advances in understanding the "big picture", we can now describe the core theory of complex analysis in, say, 40 pages, but then each of the ten important theorems become one-page consequences of this theory. By doing so, we have actually made the total amount of pages required to prove each theorem longer (41 pages, instead of 30 pages); but the net amount of pages needed to comprehend the subject as a whole has shrunk dramatically (from 300 pages to 50). This is generally a worthwhile tradeoff (although knowing the "low tech" elementary proofs is still useful to round out one's understanding of the subject).
There are very slick and short proofs now of, say, the prime number theorem, but actually this is not the best measure of how well we understand such a result, and more importantly how it fits in with the rest of its field. The fact that we can incorporate the prime number theorem into a much more general story of L-functions, number fields, Euler products, etc. which then ties in with many other parts of number theory is a much stronger sign that we understand number theory as a whole.
It is in principle possible that reviews are revised/replaced (as I assume you know).
However, as far as I know, this is mainly done to replace factual errors. From your description it seems to me that your situation might be at the borderline of factual errors and different interpretation.
You could also check http://www.ams.org/mresubs/guide-reviewers.html (in particular the point 'evaluative reviews' to see whether the review is in line with what is written there).
Yet, since you say that the review is not negative, this seems less relevant to your situation.
Now, in case you decide to do anything, in your situation it seems definitely advisible to contact the reviewer directly. As it was not negative it might be a misunderstanding/an honest mistake, and the reviewer might be willing or in some sense even happy to correct the review if made aware of the problem.
I am a fairly frequent reviewer for MathSciNet. My greatest worry doing this is to write something wrong in a review, and by doing so, somehow make a fool out of myself. So, in case an author of a paper I reviewed should ever contact me in a friendly way and point out why my review is not to the point and I then understand that s/he is right, I certainly would try to get this corrected, and be grateful for being made aware of it.
By contrast, I know indirectly (a collegue of a collegue...you get the idea) that if the reviewer does not want to change the review it can be very difficult to get it changed (except there is a direct factual error).
So, you need the reviewers consent anyway, and as André Henriques says, there is no way to hide that you were 'behind' the activity; or even if there was a way to do this anonymously, it should be the default assumption that the author of the paper is the one 'complaining'. This seems another reason for directly contacting the reviewer, as it seems rather more likely to get her/his consent by this course of action, then by one going an official way.
How to phrase the communication with the reviewer: a way could be to not directly or mainly critizise the review, but to just sent the reviewer your point of view. In other words, write somehow your own review and share it with the reviewer. Perhaps only pointing out key differences in passing.
In any case, if you do not care deeply I would at most contact the author of the review; perhaps this works out well, but if not rather drop the matter as further activity might be in vain, and not be worth the effort and negative side-effects.
Best Answer
We have had difficulty obtaining the requisite permissions from the publisher. The ICM2014 website has the Legal Disclaimer: "The Seoul ICM Organizing Committee, the legal copyright owner of the articles in the proceedings, hearby grants unlimited noncommercial download and use of the articles." This is not sufficient for our purposes. The most recent communication with them was this week. (Note: I'm the person @DanRamras wrote to.)
Update (2018.02.22). We have now received permission from the publisher, as well as physical copies of the proceedings. The papers are now in the database and available in MathSciNet. Further processing (such as reviews) is still to come. See ICM2014, Volume I, ICM2014, Volume II, ICM2014, Volume III, and ICM2014, Volume IV.