Board Game Arena

This happened recently in a game:

I had three tiles in hand, one of which was a castle. A tile appeared in black market, which I wanted to buy and play.

I couldn't buy it before playing, as I couldn't hold more tiles. So I played the castle, making space for the tile: then I bought the tile; then I used my castle privilege and played the tile. So effectively, my castle action was paused while I made the purchase.

According to the rules, I am not sure if this was right, but the system allowed me to do it so I did it.

It is allowed in 2019 edition but not in first edition - and it's implemented accordingly as both editions are available here. So maybe you looked up the wrong rules for the edition that you played (or accidently played a different edition than you usually want to)

Indeed, I looked at the old rules. I knew there were some changes (the notorious yellow tile 6 and certain bonus points) but I didn't know this was one of them.

So... I did the right thing (and won the game) and there's no need to feel bad for my opponents. Thanks for explanation.