Presumably the curtain was meant to be gold: often yellow is used as a substitute, but on its own yellow is not a liturgical colour. If that is the case then "gold" is your general, all-purpose, "bright" colour used for all Sundays that aren't in any other way special (e.g. Pascha, Theophany, Pentecost, a feast for the Mother of God etc.), and when it isn't a Lenten period.
When it comes to the Feast of Dormition, which happily for you falls on a Sunday this year, the colour will probably be blue, which is the colour used for feasts of the Mother of God.
One thing about Liturgical colours from my own experience is that there are no hard and fast rules, and most parishes will only be able to afford a set of "bright" vestments for normal Sundays and a "dark" set for Lent. They may also have a set of white vestments for Pascha. They may not even have enough for more than one set of colours (so they will usually have "gold". Colours are a tricky thing to get right (I mean the consistency of the colour, not choosing what colour represents what) and this was even more the case in times past before modern-day chemical dyeing processes. As such, most of the "rules" about Liturgical colours are heavily dependent on where they developed, and what dyes were available in those places.
What colour are the curtains, altar cloths etc.. usually? I'd be surprised if they weren't gold. It may be that coming out of Pascha (white) and then Pentecost (green), the change in colour was more striking.