You have quoted the critical part Eugenios and it immediately jumps out why the pathe are part of the canon of truth - they are analogous to sensations and function "automatically" such as not to be considered subject to error:
Rather than mapping pathē onto either the soul as a whole or the body, Konstan assigns pathē to the non-rational part of the soul, the seat of sensation. He locates the emotions, which “do not seem to have a special name in Epicurean theory,” in the rational part (11). Crucial to this schema is Konstan’s claim, based on Lucretius’s De Rerum Natura and Diogenes Laertius’s doxography of Epicurus, that Epicureans did not consider emotions such as fear and joy to be pathē at all, since emotions depend on memory and reasoning, whereas pathē do not. The upshot is that fear, as a rational emotion, involves belief and evaluation, and is therefore susceptible to error; whence the psychological roots of pernicious “empty beliefs ....
--and to emphasize the point that last sentence should say something to the effect "while the pathe do not involve evaluation, and thus, like the senses, are direct contacts with human reality to be considered as truly reported at all times."
In this analysis it is extremely useful to see that "emotions depend on memory and reasoning, whereas pathē do not."
VERY good direction I think!!