My PhD went over time - advice for explaining this on a CV
Whatever you do do not fabricate or conceal the truth. I am not sure someone would worry about finishing "on time" as much as looking at the quality of the work you have achieved. In my system there is also a 4-year research time limit (in terms of calendar time it can be extended by including teaching, maternity/paternity leave or whatever is applicable). Regardless of whether you apply for a job in academia or industry the criteria for the employment will be much more than finishing on time. So issues like quality, number of papers published, social skills, other relevant skills will be measured. If you have a reasonable explanation for the extended period of your PhD, just spell it out. Do not make a big story about it, just cleanly provide an explanation that makes the period understandable and reasonable.