Regieleki at least makes sense in Japanese, since Eleki is the loan word for electric, like how they wrote out Rock, Ice, and Steel the same way, and it's possible "Regielectric" was too long to localize like that, as it'd be the longest Pokemon name so far at 12 characters. Regilectric would work I suppose, but it looks just as weird as Regieleki to me. Drago has no excuse, just stick an n on the end. I'm wondering if they had a specific reason to go with Electric and Dragon, or if it was just random. Past their names, the first three titans have very similar movesets and stats, while the latter two are just barely imitating them. Even if their movesets might be technically better, and more interesting, it takes away from being part of the group.
It also wouldn't surprise me if they only made these two to show everyone that they can do more than just capitalize off of gen one's popularity. They could've just made Galarian Latios and Latias if they wanted to stick with Gen 3, and they only wanted to make two new mons, and it would've been a million times more understandable, and more likeable.