Hey guys, you absolutely CAN use the skip forward/back buttons on a non-Siri remote in this manner. I have a Logitech Harmony and do exactly that. It requires a little trickery though. What you first have to do is add a new “dummy” device to your list of devices in the Harmony configuration. You’ll want to use a DVD or Blu-Ray player of a make/model that is NOT in your household so it has unique IR codes not in use otherwise. DVD/BD remotes may be most intuitive since they have the buttons in common with what we want to do here.
In my case, I randomly chose a Sony Blu-ray player when adding a new device in the MyHarmony software, then named it “Sony Remote Codes”. Afterwards, I went to the “Buttons” menu (left side of the MyHarmony app); selected “Watch Apple TV” on the drop-down menu for the Remote Buttons; and assigned “ChapterNext” from my “Sony Remote Codes” device to the SkipForward button and “ChapterPrev” to the SkipBackward button. Once this is done, update your remote so the new device and button layout is set on your Harmony.
Next, what you have to do is go into the Apple TV’s Settings app; select “Remotes and Devices”; then “Learn Remote”. Once you select “Start” and are in learning mode, switch to the “fake” remote via the Harmony remote’s “Devices” menu and train the ATV on those codes. There are 2 phases to this. It will first just learn the basic commands, but you can then have it learn the remaining ones, which includes the “skip” buttons. Be sure you are training it to use the buttons you mapped to the skip buttons in the ATV activity when it gets to that point. Sometimes simply holding a button down to “train” the ATV won’t work, so just tap the button quickly and repeatedly until it takes.
Once done, you are DONE! The skip buttons will work exactly as desired. I have my channel up/down buttons mapped to the Apple TV remote’s SkipForward/Backward commands to use as chapter forward/backward. I can page quickly through the embedded chapters with the “channel” buttons, or use the skip buttons courtesy of the Sony remote commands to skip 10 seconds at a time. Works PERFECTLY!