Not much chance of it being supported under the legacy kernel as AFAICT it was never supported and we've abandoned all work on the 3.14 codebase after LE 9.0 and diverted our attention to modern (5.10+) kernels which while promsing, are still a bit work in progress.
If you can point me to some more recent Linux 5.4-ish (or newer) device tree (overlay) snippets needed to make the shield work, I'd be happy to see if we can get it working on a newer kernel.