You're absolutely correct, language is imprecise as well as text. A very young Christian reading the geneology in Matthew might be confused with the one listed in Luke which is different based upon perspective.
In the case of Samuel, Saul had two daughters Merab and Michal (1 Sam 14:49). The Hebrew spelling between the two names is very slight, one single tick mark. It is likely there could have been a translation error give the conditions of the documents being transcribed-not due to an error in the original text. However, it is to be equally noted that when one compares one part of scripture with the other, (1 Sam 14:49, 2 Sam 6:23, and 2 Sam 21:8), the full meaning of the scripture becomes clear; Merab had the five children, Michal had none. God scripture provides clarity when comparing one scripture against another and the accurate information is available if one is willing to hear it. This was always the view of Protestants. We don't attack the word of God.
One version I read spoke of ADOPTED daughters. Works for me.