r/JapanJobs

My background
South asian, 32, in Japan for about 6 years
PhD in engineering, finishing March 2027, at a national university in Kyushu
Research: signal processing and machine learning (Python, MATLAB); peer-reviewed journal papers and conference papers
JLPT N2; I can do daily business conversation in Japanese. Fluent in English.
Work experience back home, before coming to Japan:
About 2 years as a network engineer at an ISP (operations and maintenance)
About 1 year as a university lecturer (C programming, circuits, numerical analysis)
What I've applied to
Japanese companies through the 27卒 new-graduate route, some through a recruiting agent: AI/ML engineer, software, R&D, image processing, mechanical design
Some university and 高専 faculty positions
Results
About more than 50 applications so far
I usually get stuck at document screening or first interview.
I reached the 2nd round a few times but didn't get an offer
My questions
Age: Is being 32 the main problem in the 新卒 route? Do companies quietly prefer candidates in their mid-20s, even when they say 博士 are welcome?
Past experience: Does work experience in my home country help or hurt? I'm not sure whether to highlight it or keep it brief. Does it make me look like neither a real new grad nor a real mid-career hire?
Japanese level: Is N2 the real barrier? Should I hold off until I have N1?
PhD: Does a PhD in a fairly niche field make companies see me as overqualified or too specialized?
If 新卒 isn't the right route for me, what would you suggest instead?

I recently got a job that is a 6 month fixed term contract, but it is renewable for 6 months with no limit. Are these types of contracts common in Japan? Or is it pretty suspicious?

So, I've been reading that many of Japan companies want people that already obtain visa that allow them to work in Japan, because the company won't/can't sponsor (or support) the visa. I work in Japan but yet to face this kind of issue, but would love to know since I'm thinking to look for a new job.

Let's say I resigned from my previous company but still have remaining 2 years vias to expire and eventually get employed by a company like I describe above. So, what generally will happen?
Will I just work 2 years top because of the reason?
Or they will help renew the visa, since renewal is much more easier than sponsorship?
Or any other possibilities?