Yes; correct! However, in spite of this recognition, didn't Germany try purchasing the Eupen-Malmedy area from Belgium afterwards (specifically in 1926, one year after the signing of the Locarno Pact)?
I do not know about that, but if such an offer was made, it was not so much a revisionist ambition as a proposed business deal, rather like the US purchasing Alaska.
Out of curiosity--how much revanchism was there in the Weimar German governments in regards to the Sudetenland?
So far as I know, the revisionist policies of the Weimar governments were limited to the revising of the Versailles Treaty so as to regain former German territory in the East which had been given to Poland and Lithuania. The Sudetenland had of course not been German territory before 1914.
Hitler never made such an offer to Czechoslovakia (considering that he wanted Nazi Germany to annex the Sudetenland), correct?
Correct, Hitler always wanted to eliminate Czechoslovakia as a state, to break it up into separate components under German hegemony.
Bear in mind that Hitler's German nationalism was formed in the context of the Habsburg Empire, where there was an intense ethnic conflict between Germans and Czechs in Bohemia-Moravia, where the ethnic German element that had dominated that province in the 18th Century was now losing out to the upsurge of Czech nationalism. That is why Hitler was so hostile to the Czechs as a people.
By contrast, there was no ethnic conflict between Germans and Poles in the Habsburg Empire; indeed, the Austrian part of the Habsburg Monarchy can be seen as a German-Polish condominium. The lack of such conflict is the reason why Hitler was initially not hostile to Poles and the Polish State, unlike the Prussians (even the Social Democrats who ruled Prussia throughout the Weimar period were intensely hostile to Poland).
Paradoxically, despite Hitler's contrasting personal attitudes toward Czechs and Poles, the former suffered far less under his rule than did the latter, mainly because the Czechs submitted without a fight.
Not irrelevant : it proves that there was a desire for a territorial revision; that Hitler (temporarily) did not respond to this desire is something different .
A desire on the part of whom?
Is there any evidence that Hitler or any other leading figure in the National socialist regime, eg Himmler, harboured any ambition to take back the territory lost to Denmark in 1918?
Local National Socialist leaders in Schleswig-Holstein may have had that desire, but they had no influence on Hitler's thinking. His ambitions lay in the East, and I doubt that he had any desire to take territory from the Danes, a kindred Germanic people.
After all, the National Socialist leader in Schleswig-Holstein, Hinrich Lohse, was given a territory in the East to rule over, rather than being given a bit of Denmark.