I am only incidentally aware of postcards, political cartoons and the like as they relate to the ABW, but I have often thought about the relationships between the Boers and European countries. Their ties to the Dutch and Germans were strong, but that with the French is not as clear. During the 19th Century the people now identified as Afrikaners were referred to as Dutch or Cape Dutch for the very obvious reason of their common language, and the fact that the Cape had been a Dutch Colony for over 250 years (1652 - 1806). However, one might have expected a strong emotional tie to France as well, because of the large number of French Huguenots who had settled in the Cape, mainly around 1688. There are a few dozen Afrikaner surnames that are traced back to the Huguenots.
My feeling is that the kinship link between the Cape Dutch and the French had been largely forgotten by 1899, and that , if the French did tend to side with the Boers, they did so because of a shared antipathy towards the British.
Vol.III of the Times History (pages 48- 66) gives a contemporary perspective on European attitudes to events in SA 1899-1902. I think I did mention this aspect in an earlier post. A couple of sentences have it that "The British Government had made no attempt to get it's case fairly put before the foreign public. The Boers, on the other hand, had spared neither trouble or money in their endeavours to influence the European and American press".
Italy, says the TH's editor (L.S.Amery), with the exception of the extreme clerical and socialist sections was generally friendly. In Austria, the aristocracy and the official classes were influenced by the attitude of Emperor Francis Joseph ("England's Best Friend in Europe"). Other countries in Scandinavia refused to give unlimited credence to stories of British cowardice or British brutality which reached them through the continental press. Anyone interested in that aspect of the SA conflict would find much of interest in TH Vol.III.