I mean sure, it's "possible," in the sense of probability =/= 0, but that probability is still very unlikely, considering Alert 5 doesn't exactly have a history of getting that kind of insider info from Chinese sources.
Most of their site's info on Chinese military matters tend to be Chinese news sites -- if anything, if there really were big shrimp info about the J-15 crash, then we or CDF probably would have known about it before Alert 5 did.
Still, I posted a comment on the article asking them where they got their info from.
But as it sands, I think it's very likely that Alert 5 had either mistranslated the original Chinese language article, or they've accidentally added in their own baseless speculation.
Of course, I expect that if other defence sites read Alert 5 instead of searching for the original Chinese language article, they will probably mindlessly regurgitate Alert 5's statement about engine problems instead of doing their own investigation, which might result in a "consensus" that it was due to engine problems, when in reality there is not even any original rumours from the source to suggest it.