Even in the 1980s there was minimal difference between the two brands. Look at Bill Bonds at WXYZ with Action News, and it was basically all centered around Bill Bonds and his on-air presence. Ditto with Irv Weinstein at WKBW; they used the EWN name but it wasn't anywhere close to the Al Primo EWN. The brands were never uniformly applied and mean different things to different people. @HulkieD has brought up how CapCities slowly (even if unintentionally) morphed WABC into... if not a Xerox of WPVI, then obviously a station with WPVI's Action News in its' blood. It still used the EWN name, but it wasn't the EWN pre-1986.
WOIO's usage of Action News is mostly associated with the "last-place, last-chance news" uber-populist format that Bill Applegate---the same person who presided over WABC's late-80s changes---put in, almost out of desperation by Raycom, having admitted to overpaying for WOIO/WUAB when they bought out Malrite. It is a tainted brand in the market. EWN means nothing in Cleveland and hasn't meant anything since WEWS gave it up in 1990, and even then, NewsChannel 5 meant nothing when they gave it up a few years ago, aside from people likely confusing WEWS with WPTV on social media. If WOIO used EWN, it would feel tacked on and meaningless. (Yes, channel 3, then KYW-TV, originated EWN from 1959 to 1965 but it predated Al Primo or even Westinghouse's full treatment of the brand. Because of the passage of time, few are alive to actually remember when it debuted in Cleveland.)
It actually says a lot that none of the stations in Cleveland have a so-called "brand" for their newscasts: 3 News, News 5, Fox 8 News and 19 News. But does it matter? I'm from Cleveland and I can tell the four news operations apart fairly easily.