No argument here. Mikrotik should better document the mapping. 
. More suggesting/guessing as a result…
e.g. how the “bridge port mysteries” here http://forum.mikrotik.com/t/routeros-bridge-mysteries-explained/147832/1 get manifested into LLDP and CDP might vary… CDP use “interface-name” while LLDP use “interface”.
And on a CRS354, the HW offload status could effect this behavior too.
But yeah getting random results on a something like a diagnostic tool like Netscout doesn’t give one the warm fuzzies. But I do think the “impossible port” may be a result of some combo of bridge configuration and/or offload status etc. in configuration, than an actual hardware problem. But I get not wanting to guess/hope 
.