I had really high hopes for the updates that came to x11-libs/vte and to x11-base/xorg-server yesterday:
[ebuild U ] x11-libs/vte-0.28.0-r200 [0.26.2] USE="introspection* -debug -doc (-glade) -python" 0 kB
[ebuild U ] x11-base/xorg-server-126.96.36.1991 [1.10.1] USE="nptl udev xorg -dmx -doc -ipv6 -kdrive -minimal -static-libs -tslib" 5,209 kB
I did a full system update, ran revdep-rebuild and env-update, logged out of X and back in. Alas, though, the rendering problem still exists with LXterminal. The original thread about the problem can be found here. It seems that a few people with similar but different issues have been able to correct the problem. I would imagine that I will need to get a better grasp of what is causing this particular problem, and then file a bug upstream.