Hi @pav,
That is, sadly, expected. As the hue integration is of polling type, it depends on the manual request to the bridge. The differences that you see between the CCs and the main hue are because of the different polling interval (the CC makes it at ~1Hz and the main hue each 5s)
Anyway, as both are “polling” the hub, there will be always missed events, and that’s why only the “_up” or “release” presses are registered to be used as device triggers.
The Hue bridge register all remote presses, and stores the last state. The components just ‘take a photo’ of these states at some fixed rate (each 5s or each 1s). When the photo changes, events are fired (or states are updated, if there are entities involved).
To make the main hue faster, so the CC’s for remotes is not needed, use the new CC described in Custom integration to set polling interval for Friends of Hue devices - #5 by azogue
About the eventsensor CC, as you suspected, it is only mirroring the lack of some events missed by the main hue. If used over a deconz_event (using the same ZigBee gear but linked to a ConBee stick), it doesn’t miss any event.