If Liam had been under contract with Fallon's old publishing house Femperial (which would have been under the Fallon Unlimited banner) it definitely would have made for a major issue in their marriage if his plagiarism was exposed. But they wrote this story as if Liam had been pressured to write the second book by some other publisher. Ellen could have used the scandal as another tool in her campaign to drive Fallon out of the CEO chair. I guess they did not want to have F&L fighting as the baby was on the way.
I can fully understand how the writers became so divided on Adam's fate. They did not want Steven to be tainted by having killed Adam, given the fact that Adam could have easily killed Steven but (for some reason, thankfully) didn't. The decision to have Adam "reboot" as a vet in the UK seemed like an option they drew out of a hat full of random plot scenarios. Sam Underwood got precious few opportunities to interact onscreen without his American accent, so that may have been part of the reason for that location, though of course we have to hope that Kirby doesn't want a pet when she returns to London with Amanda. I felt a bit short-changed by not getting to hear the full-throated reactions of the various family members (especially Blake, but also Sam, Fallon and Amanda) to the news of what Adam had done to Steven. There just wasn't time, just as there was no time (unless I blinked and missed it) for Kirby to express her....displeasure over how she'd been manipulated by Steven-as-Graham.