Both the papers you linked to are about the kinds of pathologies that HCPs need to be aware of and look out for when doing imaging of breast tissue of TW who take exogenous estrogen. The fact that some TW who've had breast imaging show "development of ducts, lobules and acini" that on film or on screen appear "histologically identical" to some women doesn't mean they are capable of performing the same function, which is to make milk.

Pseudolactational changes have also been described

Just because the authors of this paper say "pseudolactational changes" in the breast tissue of TW have been "described" by some doctors doesn't mean this breast tissue is lactational tissue. It doesn't mean this tissue has lactated or can lactate. It means the total opposite, in fact. The clue is in the "pseud" part of "pseudolactational." Pseudo means "not genuine; spurious or sham."

Also, the first paper you cite itself says that the development of the specific kinds of tissue in the breasts that has been observed in some TW through imaging, and which you are so focused on, is the kind of development that occurs in females early in puberty, but only early in puberty. The tissue observed in TW has not reached the level of development seen in females who are in the final phase of puberty known as Tanner Stage 5.

Plus, not all breast experts would agree that the sort of tissue development that the HCPs who do breast imaging and who wrote the first paper say they have observed in some TW on exogenous hormone formulations have never been found in bog-standard males who don't take the same sorts of drugs:

Male breast pathology has a similar diversity as is seen in women. Although lobular carcinomas were not thought to occur in men because of the normally absent terminal lobular unit, several reports have identified both in situ and invasive lobular carcinoma.16,100,101 Virtually every histologic entity described in women has occurred in men.

• "Gynecomastia" in The Breast, 2-Volume Set, Expert Consult Online and Print (Fourth Edition), 2009

Since male breast tissue is rudimentary, it usually does not differentiate and undergo lobule formation unless exposed to increased concentrations of endogenous or exogenous estrogen.

Because of the [usual] lack of lobules in the male breast, lobular carcinoma [in males who don't identify as trans and don't take exogenous estrogens] is very uncommon (1%), but has been reported in the literature.

• The Differences between Male and Female Breast Cancer, 2010

https://www.sciencedirect.com/topics/medicine-and-dentistry/male-breast

Another issue is that imaging technology only goes so far and is limited in what it reveals. For example, when I had a concerning mass in one of my breasts, and a tumor in my head, the doctors who treated me guessed what the growths were made of - but they couldn't be sure until they actually took a biopsy of my breast mass, and removed the tumor from head, then sent the tissue to a pathology lab for thorough examination. In the case of both my breast mass and my cranial tumor, the doctors' guesses based on what they saw in the imaging turned out to be wrong. (ETA: these events in my medical history were separate, and did not occur at the same time. The times when I had a tumor in my head that had to be removed surgically and I had a breast mass requiring biopsy were years apart.)

The point is: even though males and females can and do develop breast tissues and pathology that can appear identical when viewed through imaging technology, there are still many differences at the cellular level. For example, the vast majority of the hormone receptors in male breast tissue will be male androgen receptors whilst the majority of the hormone receptors in female breast tissue will be female estrogen receptors and progesterone receptors. Yes, males have estrogen and receptors in their breast tissue too, as they do in other parts of their bodies. Moreover, in males who develop certain breast cancers, many of the male androgen receptors that are predominant in number will "express" in ways that cause them to behave a lot like female estrogen receptors. Yet at the same time, the male receptors that behave somewhat like female receptors will play a different role in male and female breast cancer even when the cancer is of the same type.

Scientific understanding of male and female hormone receptors is still in early stages. But what is clear from human and animal research is that whilst both sexes have androgen receptors, estrogen receptors and progesterone receptors (as well as receptors for other hormones), the ARs, ERs and PRs of males and females are different in nature, location, number, expression and function - and when hormone receptors are affected by genetic mutations, the impact of the same exact mutation on the affected receptors will be different depending on the person's sex.

Finally, the focus on breast development - on what a TW's breast tissue might look like to a casual observer on the street or what it might look like in medical imaging - is beside the point. Although human breasts serve a reproductive purpose that is extremely important, human breasts are still secondary sex characteristics. Lots of women have all sorts of breast anomalies. Lots of women have issues with their breast anatomy that makes it difficult or impossible for them to breastfeed. Lots of women have had one or both breasts removed due to breast cancer. But none of that has any affect on our sex. Many males including a majority of TW tend to see breasts as defining characteristics of women - in fact, many see breasts as women's single most important and most defining characteristic. But women don't see ourselves and each other that way.

The difference between how TW and women regard women's breasts has been illustrated on a number of Mumsnet threads where TW have expressed their belief that women size up and rate one another according to breast size, and that we see women with large breasts as being more genuinely female than women with small or absent breasts. The women of Mumsnet were aghast at this preposterous view.