The Chinese characters people practice writing for calligraphy are complicated.
The Chinese characters you learn in Calligraphy are old style characters that you don't normally use, so you can't read them.
この場合、次のような言い方ができますよ。
ーThe Chinese characters people practice writing for calligraphy are complicated.
「書道で練習する漢字は複雑だ」
calligraphy「書道」
complicated「複雑な」
ーThe Chinese characters you learn in Calligraphy are old style characters that you don't normally use, so you can't read them.
「書道で習う漢字は普段使わない古い書体なので、読めない」
old style characters「古い書体」
don't normally use「普段使わない」
ご参考まで！
カナダ 
