I saw this in an evening broadcast, on network television, in the USA, and I estimate this was somewhere in the range of 1983-1987. Whether that was the first time it had ever aired in the USA (or elsewhere), I really couldn't say. The version I saw was in English, but I don't know if that was the original language. It would not surprise me to learn it had been produced somewhere in Europe and then was dubbed for an American audience. I think that what I saw filled a timeslot that was 90 minutes in length. (I could be off by half an hour either way, but I'm leaning toward 90.) Allowing for ad breaks, this would mean the actual feature was probably no more than 75 minutes of animated storytelling.
What I saw was an animated film with a vaguely "medieval fantasy" feel to it. I don't remember guns or steam engines showing up. Here's what I remember about the characters and plot:
The good guys appeared to be a nonhuman, but generally humanoid-shaped, species who lived underground . . . or inside gigantic trees . . . or something along those lines. I believe the good guys were supposed to be much shorter than the typical adult human being. Similar to Tolkien's Hobbits, but these characters definitely were not called "Hobbits." (I don't remember what they were called, however -- it might have been a familiar word such as "gnomes," or it might have been a name invented out of thin air.)
The bad guys were members of a rival group. They averaged about the same size, but definitely were uglier. (So that a young audience could see at a glance that they must be the bad guys.) I'm thinking that at least some of them had green skin and less-human-looking facial features, although my memory is sketchy after 30 years or more. The word "goblins" enters my head -- but again, this may just mean that I thought of them that way because I was comparing them in my head to J.R.R. Tolkien's goblins. I cannot swear that the movie actually used that word in dialogue.
As the story begins, we learn that a wedding is scheduled to take place between two youngsters from the "good guy" culture. For reasons which escape me, the bad guys want to ruin the festivities. So, shortly before the wedding (which I think was supposed to take place after sunset), the bride is abducted, and one of the bad guys, who is the same height, dresses up as the bride. Apparently the sacred tradition (as explained by a narrator's voice-over, I believe) was that a bride was all bundled up so that no one could see anything of her skin, and certainly not her face, until a dramatic moment toward the end of the wedding ceremony.
Accordingly, the one scene I remember fairly well is that wedding ceremony. When it's time for the ritual unveiling of the bride, someone (probably the groom, who becomes the main hero of the story) reaches out and raises the veil . . . and freezes in shock at this ugly male green-skinned (I think) face sneering back at him. Then the ersatz bride makes a run for it, and gets away while most of the wedding guests are still trying to make sense of this turn of events.
I believe the main problem in the plot then became: "We must find and rescue the real bride!" But I don't remember exactly what sort of adventures the groom and his brave friends had to endure to achieve this worthy goal. I'm sure there was some magic involved, somewhere along the line. (I'm not sure if any regular-sized humans were involved in the plot development in any way, shape, or form.)
The one other thing I remember is the happy ending. At the very end, the bride and groom are back in their formal clothes and doing the wedding scene all over again. The narrator tells us something along these lines: "But this time, they omitted the unveiling of the bride." Even as a kid (in the mid-1980s) I thought that made no sense. Where was the benefit in quite possibly being fooled all over again about who was hiding behind that veil, and this time taking even longer to discover what had happened?
For what it's worth, the thought occurs to me that this film may once have been intended as a pilot for a new series, but if so, either the series never materialized or else I've simply never run across any other episodes of it. I don't remember the names of any of the characters, but if I ever ran across a sequel to this (whether a feature-length film or a shorter TV episode), I believe I would have recognized that it was, in fact, following up on that film I'd seen in the 1980s.