Re: I would ask you to fix what is effectively a bug (or unintended feature) that was never in the original design.
The original design, for years, has been "if no contact images, then checkmarks", so the only recent change, in the "updated design" release 1.8 was "checkmarks -> checkboxes", purely visual.
The size of the "tap sensitive" area has been 60dp for years (for phones).
Turning checkmarks / checkboxes off completely was never possible before, now it is.
Re: If right handed users really want this feature, then they have the option in settings to long press on one header and then select anywhere on multiple headers.
The one who actually ran into it seemed happy with it.
I did reduce the size of the tap area by about 1/4. Reducing it further would essentially remove the behavior completely.
Re: If you don't agree, then there should at least be an option to toggle this "new" feature that has crept into the recent update.
Right now we're at "release candidate" stage with the 1.8.2 "stable hotfix" update, there will be no more translations in this cycle, and therefore, no new settings.
In the longer term, I feel that it would be better to just decide how it should be (i.e. only long press to select when checkboxes are off, or tap to select too) and not add yet another setting.