Hi from Paris,
Daniela,
Concerning Paul, I can add these facts :

• he was Austrian : thus he was citizen of a foe when WWII started on 1939, September 2nd
• he was surely obliged to register and be detained in a French camp for German and Austrian citizen, I add immediately a camp with light rules (my Austrian-Galizianer GF & uncle were also there and I have pictures of them in this light detention of fall 1939 ).
• Foreign Jews could leave these camps if they enrolled themselves in French Foreign Legion, as my GF & uncle did.
• You can find 2 lists including Paul on this French Army web site : https://www.memoiredeshommes.sga.defense.gouv.fr/fr/arkotheque/client/mdh/engages_volontaires_etrangers/resus_rech.php
• Just type "Stransky" as name, Paul and Joseph appear. I attach Paul's documents.
• During "phoney war" (https://en.wikipedia.org/wiki/Phoney_War) most of German and Austrian Legionnaires were sent in North Africa French departments (Algeria, Tunisia), so they couldn't be fighting directly against German troops.
• You can hope to get Paul's Foreign Legion file at https://www.legion-etrangere.com/mdl/page.php?id=305&titre=Le-Bureau-des-anciens, your letter must be in French as it's our national and sole language : nobody is perfect...
• David gave you all informations to get copy of Paul's naturalization file : it should be a reason why a 1st decree of 1938 (ref 51755 x 38) wasn't officially published (perhaps due to rising concerns with 3rd Reich, Munich's treaty, etc..) and Paul had to wait (being still alive...) 1946. Obviously his enrollment had been a good reason in his file.
• I write it again : a French naturalization file contains about 20 to 40 documents with important informations about the incumbent's life. 
• "White pages" are available in France, specially when you search a not so common name as Stransky :https://annuaire.118712.fr/?s=stransky
  A person called Patrice is second in list...

Khavershaft
Bernard Flam
Archives & history of Medem Center - Arbeter Ring (Bund, Workmen Circle) of France