Consequences of taking 5 years to graduate with a double major?
Your circumstances are very different than when someone does a single-major program in five years. Two majors—in this case, both in engineering!—and effectively two minors (if you do years of Japanese and Russian) are non-trivial, and as you mentioned, trying to do it in four years would require extensive "credit overloading." If you can afford to do so, it would be better to do things well in five years rather than rush in four years and do a mediocre job, if your goal is to go to graduate school in the long term.