I wonder of ordinary filmmaker is referring to people actually testing the camera for feedback to Canon, or if these are the review units that go out to reviewers not long before an announcement? This seems pretty late in the game to be seeking actionable feedback on the camera if it is truly going to be released before Q1 2024.
Toward the end of development, almost 100 percent of the design changes/fixes are software. That also needs intensive testing. My sense is that this is a three-quarter-long process, but almost entirely internal to Canon.
The Japanese corporation is almost completely responsible for camera design, and all other national/regional corporations are just fully-owned subsidiaries that deal almost exclusively with sales, distribution, marketing, local legal, support, and major client business development. When a PR exec in UK lets a few press people handle a pre-release R3, that puppy is done. The physical camera might be a pre-release version, but the designs are locked, and the often-underestimated manufacturing design process is ongoing. Feedback coming back to that national office may well not make it back to the right people in Japan. A hardware suggestion is likely to be dismissed, out of having become accustomed to being completely ignored on these. A software suggestion is more likely to be forwarded.
Press events where they fly YouTubers to a location to test out the camera will have people assiduously writing down feedback and notes, which helps give the impression of listening while also indicating a pre-release status of the cameras being tested. Because the actual Japanese product managers are typically present - or at least aware - this feedback is likely to be heard by the development team. Because that team at that moment is then oriented toward fixing some hair-on-fire manufacturing issues prior to release, almost any feedback acted upon will be from among the software suggestions, and come out in the 2nd firmware upgrade if at all.
Component manufactury and assembly in the 5 and 1 series are typically done in Japan, so there is less lag time required in that series. When something is manufactured partly in Vietnam and/or China, the lag time for changes to work through the changed manufacturing process is a few months longer.
The profitability of the 5 series line is in good part due to how well they manage the design's manufacturability, and this is typically the main concern at the point we hear a rumor about a camera soon to be announced.
For my part, there are a few features that would be nice to have that others have mentioned, but nothing must-have. Pushing the resolution up would actually be nice for me, and suit Canon's aim of getting pros and amateur$ to feel the need to buy both the R5 and the R1/3 series (yes, the R1 will disappoint everyone looking for high res). Right now the R5 is a goldilocks camera, which Canon may feel is giving too much away. Canon does often create new versions sometimes primarily for reducing manufacturing costs. I suspect there will be a few nice-to-haves with the R5 II, but the manufacturing bill will be reduced by 15-20 percent.