Sure. But I strongly doubt "around" can in any way be the appropriate word for 1,000 kilometers away.
So the settlers would have had to go much further into the lands to find gold.
ANd to have such a great trek to what was to become Transvaal, you would need :
- either the same process as happened in the british colonies on the north american continent or in Australia (a big enough population base on the coast so that there is demographic pressure for pushing deeper into the continent in order to grab new lands),
- or the same process as happened in South Africa OTL (a first group of settlers living on the cost is conquered by a foreign power and, not wanting to live under these conquerors' rule, moves deeper inside the continents).
I strongly doubt the second hypothesis could have happened much earlier than it did OTL.
The first hypothesis would be possible if you have a significant flux dutch of immigration heading directly towards South African rather than heading towards the Americas as it did OTL.
You need much more than the 1300 european settlers that lived in South Africa by 1700. And you need to butterfly away the halt on immigration that was implemented OTL in 1706. You need far more than only 60,000 people, slaves included, by 1800, or you need them to have a strong inventive to move inland which would be weird because they naturally need to be close to the coasts.