Yes, Lishu is the underage consort. She's 14 in the manga but in the novel she is now 16 years old. Basen's family already informed the head of Lishu's clan (Lishu's grandfather) that they have the intention of Basen and Lishu to get married if the grandfather permits it. We still don't know in the novel if the grandpa will allow it. Lihaku and Pairing are still not official but Lihaku wants to buy Pairing to become his wife. It does not happen yet in the novel.
Yes, there is already an official translation year ago. The official translation has volume 11. The link is below. You can download the volumes of the novel. I recommend you download the epub. Just scroll down below to see the download option and click epub. Then, you will see Volume 1 - 11. The phasing of the manga is currently on Volume 4 Chapter 12, so the novel is really long ahead. The link is here: https://archive.org/details/the-apothecary-diaries
Spoiler
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According to the novel, these are the following characters that has romance in the story:
*Jinshi and Maomao (Jinshi doesn't want Maomao to steal her freedom. There was a point in the novel that they should sleep together and Maomao knows the consequences of it that the moment they made love, she will no longer be able to leave the inner palace like what happened to Lady Ah-fou when she slept with the Emperor. Jinshi love Maomao but she dismissed him that night because he placed importance in Maomao's freedom. The emperor and other officials are pushing Jinshi to take a consort)
*Lihaku and Pairin
*Basen and Consort Lishu (Lishu will no longer be the emperor's consort later on. She is like the daughter to the Emperor and Lady Ah-duo)
* Lahan and Yao (Yao is Maomao's friend who came from a noble family and they both working in medical clinic inside the palace later on in the story)
*Kan Junjie (Lahan's older brother) and En-en (she is also Maomao's friend and co-worker)
*Baryou (Basen's older brother) and Chue (spy of the imperial family). I really love Chue in the story.