'4K' is a bit of a catch all phrase which can be misleading at times.
It looks like your AVR will be fine with some '4K' Sources - what is not so clear is will it work with 4K UHD Sources which require support for 3860x2160 at 60/50/24p with HDCP 2.2, many 'older' devices labelled as '4K' only support HDCP 1.4 and can be limited to 3860x2160 at 30/25/24p. It will therefore depend on which Sources you intend to work with.
Your cables are likely OK for 4K UHD as they are relatively short - time will tell though!
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