Couple of interesting points. First of all you have to love the reference to "English" as לשון ענגלאטירא, the language of Angleterra. Fancy. The translation was made by David Levi (see here for my prior posts which mention David Levi, that most interesting of 18th century British haberdasher talmid-chachams).
Secondly, I thought this reference to horseradish as marror was interesting.
The "green top of the Horse-radish?" Do you know anyone who uses that, rather than the root? Are all of us who use the grated root being fools? (Full disclosure: I don't use horseradish at all.) How interesting.
Incidentally, in the early days of using horseradish for marror, most likely people did use the leaves. After all, the Semag quotes Rabbenu Tam prohibiting root vegetables for marror. The Maharil forbids using the root based on Rabbenu Tam. Many, many other halachic sources also forbid the root, which of course only highlights the fact that people were using - the root. Later, the Magen Avraham and others recognized a compromise: the leaves should be used for marror, and the grated root for korech.
Finally, since we're talking about Haggadahs, here's an example of an editor who didn't just talk about making an emendation, he went ahead and did it. I'm talking about the problematic phrase from bentsching, where God's hand is described as "full, open, holy and broad." With the change of one very similar sounding consonant in Hebrew, the phrase becomes "full, open, enlarged and broad."
This is from a Haggadah from Leipzig, 1844 (here; unfortunately the title page is missing and I have no other data):
See Baruch She'amar by Rabbi Baruch Epstein, page 211-2, for a good explanation of why הגדושה makes more sense than הקדושה. It will of course be observed that R. Epstein (b. 1860) obviously was not the first to be struck with this idea.