My mom, who used to be an *awesome* gardener, used it exclusively on everything, and that was over a quarter century ago, back before they had figured out how to "remove" the stink!
Maybe it's just a case of "boy follows mother's advice when he grows up" but, we use it here as blossom booster, and I think the stuff is terrific and gives awesome results.
Only problem is, the Alaska Fish Fertilizer company has gone out of business. We have a few jugs left but, when they're used up, we'll have to go to something else; I don't know what yet.
If there are any downsides to fish emulsion, I don't know about them; maybe someone else who's had experience with it can post.
Anyway, my two cents says go ahead and use it, dilluted as usual. It'll take about 3-4 months before you notice any difference (as with most everything else orchid-related, noticeable change comes slow), but when you finally do see a difference, I think you'll like what you see.