I noted that an English machzor from 1796 actually also transliterated it as "mea raglayem" in the translation - but it included a footnote explaining that this means Urine. My guess was that at the time some people read the prayers from the English, and while the translator (David Levi) had no problem letting people know what the word meant, he figured it was nicer for them to read "though mea raglayem was proper for the purpose . . ." rather than "though Urine was proper for the purpose . . . ."
In either case, we see that in 1949 Philip Birnbaum felt that urine should not be mentioned in the synagogue. I came across David de Sola's translation - although this particular book is from 1878, I believe his translation goes back to the late 1830s.
As you can see, de Sola primly writes that "another substance" could have been used, but was not decent to bring into the Temple.
Here is the title page:
I was curious how a contemporary of the Birnbaum siddur, a siddur published by the Rabbinical Assembly in 1946, translated it. They took the easy way out - there is no פטום הקטורת, not after mussaph and not before shacharis (although I might add that it kept both sיקום פורקן!).
In 1839 Jeremias Heinemann published a very interesting book called the Hebräisch-Deutsches kursorisches und alphabetisches Wörterbuch zum allgemeinen Siddur. I have never seen anything quite like it. What Heinemann did was to go through the tefillos, prayer by prayer, and list all the principle Hebrew words with German translation. I suppose I have to think about it some more, but on the face of it it seems like one of the most effective methods of learning what the prayers mean that I have ever seen. It's a fascinating work - it begins with Mah Tovu, and just plows through it all, including the 15 Shir Hama'alos and the complete Pirke Avot after Shabbos Mincha (and, yes, it includes Yekum Purkan).
Here is how he translates our mei raglayim:
Nahme für Urin. I guess the Germans were less timid than the Anglos.
Heinemann is an interesting person. He was a modern educator in Berlin, originally associating with the Reformers in the 1810s, but he became more traditionalist. Apparently recognizing his valid role as a positive, modern influence, Rabbi Akiva Eger gave a haskama and subscribed to one volume of his edition of Mendelssohn's Chumash (with the addition of his own commentary). Another example of Rabbi Akiva Eger encouraging a similarly modern-leaning type of rabbi is Salomon Plessner, who was a noted preacher and translator of the Apocrypha into Hebrew. With Rabbi Akiva Eger's approval, Plessner published עדות לישראל, a book full of quotes by Gentiles about how wonderful the Talmud is. See here.
Getting back to urine - it is interesting to take note of the fact that apparently the idea that urine could even have been considered in the first place was considered shocking, so there are traditions which deny that mei reglayim, in this context, meant urine. Probably most famously there is the Kol Bo (#38), which says the following:
Namely, "some say that mei raglayim come from a certain spring called Raglayim; it is not possible to say mei raglayim literally (i.e., urine) since God forbid that it should enter anyone's mind to include urine in the making of the incense." According to this interpretation, then, what was proposed was that water from a spring called Raglayim might have sufficed for the incense. Since "water from Raglayim" is the same word/ name as mei raglayim, i.e., urine, then it would be wrong to use an ingredient with the same name as urine. But urine itself? Come on, don't be ridiculous. This interpretation seems to have been accepted as the best by Seligmann Baer, for he quotes it on page 248 of his siddur Avodas Jissroel, and even supports it by noting that the book of Joshua mentions an עֵין רֹגֵל numerous times. The Machzor Vitri gives the spring explanation as well as another one: יש אומ' עשב הוא ששמו מי רגלים ויש אומ' מעיין הוא ששמו מי רגלים ועזין הן וריחן רע - some say it's an herb named mei raglayim, and others say its a spring called mei raglayim, [with water that is] pungent and smells bad.
If I remember correctly, in David Golinkin's edition of the responsa of Louis Ginzberg, there is one letter from someone asking Ginzberg about this, and Ginzberg replies with some sources and also tells the correspondent that he is surprised and pleased that anyone in his time (1930s?) even cares about this.