So in iMon Manager I have the repeat delay set to the second tab from the left and the repeat rate to to the 6th tab from the left.
In the Harmony software I am using the "Silverstone LC-20M" device. I am honestly not sure if this is still the device that the harmony team hand crafted for me or if it is more "off the shelf". I definitely had a custom device for my Harmony 895, but I cant remember if we moved it over when I got my Harmony 900, or if i was able to stick with the then current off-the-shelf device. I will PM you my Harmony account ID and if you want you should be able to call them and get them to copy my device to your setup. They have done that in the past.
Anyway, either way, I can see that I have learnt a few custom keys - a few random keys that seemed to be missing but, most importantly the arrow keys. If you do get my config the arrow keys I am using are named "Direction up/Down/Left/Right" and they are custom, but "Analysed" (not RAW). I remember from 6 years ago when I first got my iMon the arrow keys ARE tricky. Because the pad duplicates as a mouse they seem to send a stream of coordinates, rather than normal keystrokes and it is the iMon software that interprets them. This means if you learn the arrow keys, unless you are very careful when you press them you will get something like "up a bit, up a bit, up a bit, left a bit, up a bit,right a bit"......!! it might be worth trying to relearn the arrow keys a few times, with quick presses, as accurately in the middle of the direction you wish to learn as possible (or just get my config transferred over!).
Other settings are:
Power on delay: 2000ms
Inter-key delay: 0ms
Inter device delay: 50ms
Repeat setting: 2 (advanced troubleshooting)
I hope this helps. It was a bit of a pig getting this working some years ago. The iMon Manager seems to work better on W7 than it did on XP (less lag). But I promise all is working great here now.