The swim descriptions in my training plans can be done in metres and/or yards, depending on what you prefer to use. My plans are used globally, so I cater for both units of measurement.
I generally make the swims a little longer than I would normally, to allow for the fact the swims are around 10% shorter for those people who train in yards.
You should set your Training Peaks account to default to Metric or Imperial.
If it's set to Metric and you swam the workout in a Yard pool, Training Peaks would (for example) convert 1969 yards to 1800 metres. You can change this, by changing your default units from metric to Imperial in your Settings.