9x12 film is not a real problem as it is widely available in Europe.
Whilst the KW etui patent cameras are a design ikon, I not not sure they would stand up to much use after so many years - they are more sensitive than other designs. I can speak highly of the 9x12 by Glunz, Goerz and Zeiss-ikon which are very available and robust. The film holder situation is not that difficult - but be aware that sellers have no idea what they are selling. They are so cheap that an occasional wrong purchase will not set you back much. There is some info available on line about style differences. I enclose a small contribution from a 1934 catalogue which shows the main types in profile/camera producer. The weakest point is the velvet light sealing strip which has occasionally been eaten by various bugs.
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