Japanese circuits are normally published in English too, so you don't have to worry about the language.
German is mainly used in Germany and the schematic symbols used are DIN, while anglo-saxon countries use ANSI symbols, e.g. the ANSI symbol for a resistor can be misleading in a DIN oriented schematic. Using DIN that symbol stands for an inductance with an air coil.
The greatest difference you will find concerning Boolean logic symbols. Check the attachment for comparison.
You also won't have to worry about the language. Knowing ANSI and DIN will be fine to read every schematic.
There are also differences concerning part descriptions. A transistor for instance is called "T" followed by a number, which I find logical since "T" stands for transistor, ICs have the part discription "IC".
Anglo-saxon schematics use "Q" for transistor and I don't know about such a thing like a "Qransistor"
and instead of using "IC" they are named "U"
Regards
Boncuk