I think the increase in penalties (holds & false starts) for Ifedi are directly related to his struggles playing the tackle position at the NFL level.
Take a look at Ifedi's combine numbers: he had an explosive broad jump (109 inches) but a very slow short shuttle time (4.75 seconds). In fact, Ifedi's short shuttle at the combine was the exact same as James Carpenters' time, another college tackle who lacked the lateral agility to play the position well against outside speed rushers at the NFL level. The tape bears this out, as well.
This doesn't mean Ifedi is a bust. He has the potential to become as dominant a guard as Carpenter, and he showed flashes of explosive run blocking as a rookie playing the RG position.
Unfortunately, the Seahawks are in short supply of tackles, and Ifedi was basically forced to play out of position by necessity. Moving outside increases the likelihood that Ifedi will try to compensate for his limited lateral agility by either trying to get a jump before the snap (false start) or resort to holding once he has already been beaten around the edge by a more agile outside pass rusher.
Next season, however, the team will have two starter caliber tackles on the roster in Duane Brown and George Fant. If one of those guys can learn to play the RT position well, that would allow Ifedi to return to his more natural position at guard.