This may have been asked, and i do doubt it but here goes.

There were reports of the placard showing the plot/ward reversed.

Did they hotfix this, and if so or not, could this have caused the housing error?

Here's a quote on the lodestone from a dev.
"Thank you for reporting this! It will be fixed as soon as possible. (Also we confirmed it's just a text issue, so don't worry - you should still be registered for the correct plot!)"

Notice it says "should still be registered....."