There was no such thing in the Seleucid Empire as machairophoroi epilektoi as far as we know. The word "Machairophoroi" was variously used in several kingdoms (although best attested in Egypt thanks in large part to the papyri), generally in reference to either police, paramilitary, or militia-type units who were probably armed with a thureos or pelte if/when they carried a shield at all. EB2 includes machairophoroi as a unit suited mainly for garrison or irregular duty; after the unit was designed, a member who was also with RS2 ported the concept there and expanded on it. Machairophoroi Epilektoi is a reconstructed name, and not a bad one, but it is reconstructed, and I would guess, based on Hellenistic military nomenclature, that the Seleucids probably would not have selected a name like machairophoroi for an elite, front-line unit.
On the subject of the machaira itself, 2nd century evidence indicates that the "machaira" wielded by these and other units may have been a different style of weapon, influenced by Galatian contact, a double-bladed weapon with a stabbing point. While it would have been more effective than a traditional machaira in thureomachy, it probably would not have performed very well against Roman gladii, particularly the longer, stronger, and broader hispaniensis of the second century. Note, for example, that RS2 has that detail correct: the machaira wielded by the machairophoroi epilektoi are these second century types, not the classical machaira. I just think thorakitai epilektoi would be, historically, a sounder name. But I'm not very familiar with their roster, perhaps they have both and needed another name for the sword-armed unit.