Well if your device is calibrated in windows properly, I would say it is more of the behavior of the particular plane you are flying.
While I have not flown BOS in some time, I do see similar in TF Cliffs, more so in the Hurricane. And of course different speeds require different levels of trimming.
Some of these planes do not have certain trimming available, I get around that by indeed using a TARGET script, I can trim both my y and x axis on my Warthog stick, I have mine programmed to the HAT 1, using the paddle as a modifier.