Unfortunately, we were forced by Apple platform (due to compilers) and Qt (because of upgrades) to upgrade our dev tools and build machines to 10.12 versions. And unfortunately, this means that application needs to run on 10.12+ versions.
The previous version of dev tools contained the critical bug which caused random crashes and the only way was to upgrade to Qt 5.9.
In compare to Windows, where we can compile on latest Windows10 and still were able to support also WindowsXP, OSX/Linux has the design that it's necessary to compile on the oldest supported version.
This means to keep up to date old Linux and OSX versions and sometimes when there is critical bug this means we have to update to higher version.
We're sorry for this but are not able to solve it in any way. This upgrade affects only a few users because most users in OS X ecosystem keep our systems updated.