Show me sale transactions in Cornwall Gardens and 2 Yishun Industrial Street 1, office.

The query you provided seems to be mixed, as it mentions both Cornwall Gardens and an address at 2 Yishun Industrial Street 1, which is not relevant to Cornwall Gardens.

For sale transactions of landed properties in Cornwall Gardens, here are some recent examples:
- A Good Class Bungalow (GCB) in Cornwall Gardens was sold for $18.6 million in October 2019, sitting on a 16,329 sq ft site.
- Another GCB in the area was sold for $47 million in September, on a freehold site of approximately 21,800 sq ft.

To view more detailed and up-to-date transactions, you can visit the EdgeProp Singapore website and search for Cornwall Gardens under the landed property section. This will provide you with a comprehensive list of recent sales transactions and other relevant details.