I do have the book Toldos Yitzchak which I have not read through fully. It's not an easy book to read because it is written in old rabbinical idiom, is extremely verbose, and the author moralizes for most of the book and just includes biographical details in between the moralizing.
She says she will translate or make copies of pages for me for a fee, but she doesn't sound terribly enthusiastic. She does provide me with some interesting leads that could be helpful, one to a rabbinical genealogist is Israel and the other to the editor of Yated Ne'eman in Monsey NJ. That is R. Pinchos Lipschitz, a great grandson of none other than Ya'acov Halevi Lifschitz, the author of Toledot Yitzhak.
All that was very interesting, as was an article she attached, "The Reliability of Genealogical Research in Modern Rabbinic Literature," by Rabbi Meir Wunder. It is very long and in some places arcane, but contains some important ideas. I will excerpt one section about genealogical errors and the concept of yichus, or lineage, and then urge you to go to the full article on the JewishGen.org Rav-SIG online journal.
Moving on into the second half of the 19th century, we do have famous experts in rabbinic genealogy, but even so, their writings include guesses, assumptions, and mistakes. They were very knowledgeable, and in their period the genealogical data of families were preserved, but they had no sure means to check the veracity of their findings. Contact was through letters, which were slow; very few managed to make use of the libraries of Western Europe with their important manuscripts. Poverty was rampant, and one way to put bread on the table was to research and edit yuchsin scrolls for the wealthy who had money, but still lacked the prestige of great lineage. Thus, if the facts were shaky or uncertain, one might build castles in the air without a solid foundation. An example of this is relating the Maharsa, Rabbi Shmuel Eidls, back to Rabbi Yehuda Hechasid, which is totally false, because the Yiddish names Berish and Mendel, in the chain, were not known in the middle ages in Germany.
Inexact terminology also makes it difficult even to this day to clarify yuchsin. Terms such as neched (grandchild), or she'er besari (my relative), or mechutanim (in-laws) were used to describe much more distant relationships. Another example of lack of clarity occurs when someone writes: “Yitzchak the son of Avraham, the rabbi of such-and-such a community.” Who was the rabbi, the father or the son? Other proofs are needed to make that clear. The lack of punctuation, especially commas, causes confusion. If it says, “Yitzchak son of Avraham, son-in-law of Reuven,” then Yitzchak is the son-in-law. But, if the comma is omitted, then Avraham is the son-in-law. In cases where someone married twice, it may be unclear who was the mother of each child. This fact would affect the whole chain of yichus.