Chelvel,
Also offers sage reasoning. I thought about it and worked a compromise. I reinstalled the original 100mm stem, inverting the small positive angle to a small negative. My bar is now a little further away and a little lower, much less than 10cm. The handlebar is a little lower than my saddle, instead of higher/even. I made a test ride just before dark and it felt better.

Tomorrow I will do a longer ride and test it more thoroughly to see how my neck and hands adjust to the change. Sometimes muscles get stronger and more flexible, which may help even nerve issues. Even old battered bodies can adjust, especially if one makes changes gradually, which is at least one reason I have three different stems to switch between.