I might have missed it in your earlier post, but I haven't seen a link to where you got the code from. You indicated
Project name is Experimental Aircraft Electronic Flight Information System.
It was designed by Oleg ?
which makes it difficult to find. Post a link.
The wire library (for AVR boards like Uno and Mega) was last modified in 2012 (according to the text in the wire.h and wire.cpp files).
You can search your computer for those files; on my windows system (windows with IDE 1.8.5) they are in C:\Program Files (x86)\Arduino\hardware\arduino\avr\libraries\Wire\src.