But as a proportion of GDP the terms of the Franco-Prussian War were worse then Versailles.

source?

Germany didn't actually pay much of the money demanded at Versailles despite it being lowered multiple times whereas the French did.

He because the number was ridiculous high and it is highly questionable that Germany was actually able to pay it.( Just read what Keynes thought of the Versailles treaty and how he evaluated it economically.) Also we're not only talking about cash flow, but the loss of economic relevant resources e.g. almost the whole commercial fleet which made export impossible for a while, overall it payed around 21-78 billion Goldmark and also payed further reparations for WW1 after WW2. The initial demand was 280 billion Goldmark, whereas France paid 5 billion Franc

revanchism centred around the lost French regions but the occupation of northern France until the money demanded was paid didn't help.

(That sounds familiar) [https://en.wikipedia.org/wiki/Occupation_of_the_Ruhr] but of course it I never claimed that the demand of Reparation payments and its realization was rights I only said that your facts regarding the reparations are wrong and French revanchisms is surely understandable to some degree.