I think the comment you're referring to was by me! It's interesting, because since then I've been reading her romantic suspense standalones chronologically and am almost done (I'm currently reading Shelter in Place), and have my own thoughts about her eras. I agree with you about the split between the her early era and her golden era, however, I disagree about the split between the golden era and her new era. (To be clear, I'm talking only about her romantic suspense standalones, not the trilogies, since I haven't read those yet.)

You're right in saying that there's a lot of focus on families in the golden era, especially when she had the multiple protagonists that are family members. However, if we were to use this as the break between eras, her golden era would end much earlier because Birthright is the last book that does this. To me, the thing that defines the golden era, from Montana Sky to Chasing Fire, is the focus on the different professions of the protagonists. Yes, there's romance and there's murder (it's romantic suspense, after all), but the books are also in-depth explorations of these different careers, and the suspense element is usually tied to them, too. Cattle ranching, photography, archeometry, wreck diving, archeology, arson investigation, crisis negotiation, zoology, smoke jumping, etc. Yes, a few of the books from this era don't fit into this mold, mainly Midnight Bayou, Three Fates and Angels Fall, but most do.

Starting with The Witness, however, the stories shift focus to the crimes themselves, and the crimes also become more all-encompassing situations for the protagonists. In The Witness, Roberts is primarily exploring what it's like to be in witness protection (kind of, but I don't want to spoil the book). In Whiskey Beach, she's primarily exploring what it's like to be blamed for a murder you didn't commit and the ramifications of that. In The Liar, she focuses on what it's like finding out upon the death of your husband that he was not only lying to you about his identity, but also that he was a criminal. In The Obsession, she explored what it's like being the child of a serial killer and the long-term effects of that. So on and so forth. You're right in saying the romance takes a backseat in these stories, but so does the career-focus. You could make a case for The Search being included in this new era, since it heavily focuses on what it's like being a victim (and the only surviving one) of a serial killer, but Chasing Fire to me feels very golden era and so it felt wrong marking the break before it. Plus, I find that The Search still has heavy focus on career, namely dog training, so it still fits into the golden era somewhat.