> [referring to Microsoft Word 1.1] It seems that this code is from a C project created recently in GitHub. No sign that’s a code from 25 years ago.

I wouldn't necessarily say that. At a glance, there are some questionable idioms: assignment inside a function argument (especially problematic since argument evaluation order is unspecified), old-style argument declaration, a custom Boolean type, less-than-descriptive variable naming, etc. I wouldn't let any of that pass code review today. :)

> The power of C is its stability over years, it remains basic, no advanced mechanism was introduced to the language, the code still simple to understand and maintain.

Not when you take the arcane undefined behavior rules into account. C semantics are anything but simple.