The Triage X Wikipedia page states that the show was picked up by Sentai Filmworks back in 2015 for an English release.
In May 2015, Sentai Filmworks licensed Triage X for an English-language release in North America, [...].
Other than that, I can’t seem to find anything else regarding the dub.
Was it ever completed?
No, there's no English dub for Triage X (as of April 2019).
Anime News Network listed Sentai Filmworks as one of the English licensors for Triage X, but there's no English cast (compared to the German's which was dubbed by TNT Media).
English cast
(none)
English companies
Licensed by:
- Animatsu Entertainment (UK & Ireland)
- Madman Entertainment (Australia & New Zealand)
- Sentai Filmworks
They release the series as a complete BD-box (Japanese audio with English subtitle)
TRIAGE X COMPLETE COLLECTION
SENTAI FILMWORKS
Language: Japanese with English Subtitles
Regarding the statement on Wikipedia, the earliest revision already stated that "In May 2015, Sentai Filmworks licensed the series for an English-language release in North America" citing Sentai Filmworks' official announcement. The announcement only stated that Sentai Filmworks licensed the series (which is correct) but didn't say anything about English dubbing.
I think the quoted statement from Wikipedia might be ambiguous and misleading since it might either mean "English-language release with English subtitle" (which is correct) or "English-language release with English dub" (which is wrong).
