All X-T4 cameras we buy in Europe are made in China. Fuji only delivers 'made in Japan' X-T4s to the USA to bypass the high trade tariffs imposed on Chinese products. In fact, I've been told (but I'm not certain about it) that these cameras are also mostly made in China, but then shipped to Japan for some final assembly and packaging. Just enough to qualify for the 'made in Japan' stamp. Today, only the X-Pro, X-H1 (until a few months ago) and the GFX are actually build in Japan.
As for the SD card issues, that is a recurrent issue with Fuji cameras. The X-H1 had real issues (incl. lost images) and we've seen multiple reports of X-T2s, X-T3s and X-Pro3s having issues. Most of them are solved in firmware updates (the notorious 'various other bugs') but for the X-H1 I've experienced continuous problems up to date (albeit less than when the camera was first released).
Best advise is to stick to the brand and type of SD cards that Fuji recommends and hope for firmware updates. In case the camera frequently freezes, I would always ask for a replacement.
