Why is this sentence written like this? "It is interesting that the use of the “hope” word group (elpis and cognates) is found only in Titus and 1 Timothy—yet another way that these two letters are the most similar among the Pastorals." Do you mean hope is only listed in the Pastorals in Titus and 1 Timothy, not 2 Timothy? Because is certainly is elsewhere in the NT.
Ben Witherington III, Letters and Homilies for Hellenized Christians: A Socio-Rhetorical Commentary on Titus, 1–2 Timothy and 1–3 John, vol. 1 (Downers Grove, IL; Nottingham, England: IVP Academic; Apollos, 2006), 188.