Samantha007 : Actually, yes, I do, although I admit I haven't spelled it out very well yet, so I take the blame for the lack of clarity. First of all, many cis men produce *slight* lubrication on sexual arousal; it's "pre-ejaculate," the little drips that show up long before orgasm. This fluid is produced by the Cowper's glands, which is analogous to the Bartholin's glands. The location is, as I noted, different, and the delivery mechanism is via the urethra, but that's an inarguable biological fact : even cis men's Cowper's glands make fluid during arousal. It seems fairly straightforward that trans women, with the same set of internal glandular equipment, should at the very least be able to produce the *same* fluids at the same times via the same mechanism as cis men, right? And since the amount produced varies by man, it stands to reason that it might also vary by trans woman (some trans women report producing more on HRT than they did before, but that's admittedly anecdotal). The main difference in a trans woman's anatomy is that the urethra, leaking fluid and all, has been repositioned so that it will [incidentally] drip into the vagina directly.
That established, the only point of contention is how much that fluid can come to resemble a cis woman's instead. To me, it makes sense that since both mucus and other liquids produced by the body can vary somewhat based on something as simple as how much water someone has had to drink, estrogen might well change the consistency to something thinner and lighter and more "lubricating" than a cis man's. Therefore, as I said, I don't have any problem believing HRT might do that - but I can't argue if you disagree with that part.
Also, though I prefer not to think of it this way, if any liquid is produced at orgasm it is also analogous to semen; everything that produces semen *except* for the small component that is sperm is intact in a trans woman, including the urethra (albeit shortened).
Personally, I don't find that either liquid resembles semen in me anymore, but I don't have any way to prove it and I accept if you don't believe it.