I use expand to expand tabs to spaces. For utf8 files expand doesn't work correctly. E.g. in ć\ta tab is expanded to 6 spaces while in a\ta to 7 spaces.
How do I make it work for utf8 files?
You could use a short bit of Python3 code, and just pipe the text thrugh it:
#!/usr/bin/python3
import sys, os
for line in sys.stdin.readlines():
sys.stdout.write(line.expandtabs())