Did Ranma lose his (her?) virginity in the Ranma 1/2 anime series?
There certainly is no virginity losing that I have noticed in Ranma 1/2. Neither the Manga, nor the Anime have anything of the sort. 

That said, there are numerous bath and shower scenes. Doing a google translate of the page, extends the next line after what you have noted. 


  the master Chen is about to suffer a collapse when stumbling over a mountain of intimate clothes.


Judging by their description, I would assume "Chen" to be Happosai, the lecherous teacher of Ranma and Akane's fathers. 

This leads me to believe that the scene in question, using memory offhand, is from one of two or three episodes. 


Bathhouse Battle! We're in Some Hot Water Now


   In this episode, the Tendo's bath is on the fritz, and so everyone must use a public bathhouse. Ranma is stuck with keeping Happosai out of trouble, which proves difficult. 
 This episode also has a part in which Ranma is knocked unconscious, which could explain the stumbling in a trance. 

Rub-a-Dub-Dub! There's a Pervert in the Tub


   This episode is less likely to be the answer, but it does cover the theme of Happosai and Ranma at some sort of bath. Akane goes on a hot springs trip with some friends. This hot spring, as it turns out, is the hiding spot for Happosai's ultimate technique. Of course fighting between the two occurs, and Ranma, in female form, ends up inside the hot spring (thus returning to male form), surrounded by girls, which is a scene that they could be misinterpreting.

The Mixed-Bath Horror!


   This episode, also seems unlikely to me, but the Tendo Family, the Saotome's, and Happosai got to a hot springs resort. Once again, Ranma and Happosai have a battle in the baths, with Ranma being transformed into a girl, and chasing Happosai around. 



Those are what I can think of off hand, but honestly the article reads more to me like someone who happened to catch a few episodes of the show, and didn't like the themes therein, and so wrote an article with a bit of embellishment.

It's more up to interpretation. If someone has more traditionally wholesome views, they will tend to see minor lewdness as something much worse. The same with people who aren't bothered by lewd act, only in the opposite direction. 

I would check around a few of the episode I've offered, and maybe kick around the wiki a bit, if you're interested in finding more information.