Well I guess I’ll share my partial success on this.
I can use the fwk-lilac-27116 branches of both the EC and Zephyr code, and once I noticed that zephyr main’s west.xml file was pointing to a difference SHA for the cmsis module, I was able to complete a build for lilac.’
So @DHowett ‘s environment works to build lilac with the following changes
<project path="src/platform/ec"
name="EmbeddedController"
remote="framework"
revision="fwk-lilac-27116"
groups="paygen,firmware" />
<project path="src/third_party/zephyr/main"
name="zephyr"
remote="framework"
revision="fwk-lilac-27116"
groups="firmware,zephyr" />
<!-- This module's SHA should match zephyr/main's west.yml file -->
<project path="src/third_party/zephyr/cmsis"
name="chromiumos/third_party/zephyr/cmsis"
revision="4b96cbb174678dcd3ca86e11e1f24bc5f8726da0"
groups="firmware,zephyr" />