I think, and everyone might agree to it, that downgrading to an old kernel with its security holes and other already fixed stuff is IMO a very bad and dumb idea! Downgrading a kernel for a single app is always the most wrong policy.
You should note, that the last running libreoffice version was one version below the actual version in debian/stable. And note, too, that it ran on linux-image-4.11-XXX, the latest kernel version in debian/testing on an i386 system.
Mine is an EEEPC 1005HGO.
So. the better solution is, for the time, libreoffice is not fixed, use an alternative. I suggest Abiword, as it is most compatible to libreoffice and can read and write most documents formats very well (better than calibre, sorry guys).
I suppose, the developer team is working hard at the moment on libreoffice, to get it fixed. We should give them the time, and hope the best.
For me, using Abiword with the latest kernel is the better solution!