It's not-not a problem, but I don't see it as a big problem.
When I look at the Asia Pacific, I'm not overly concerned with what Japan did a century ago, I'm more concerned with what's happening right now. North Korea's at least being horrible to only its own people, but then we consider Myanmar, the situation on the border with India and China, China's actions in Tibet and with the Ughyrs, and everything else. Being concerned about both of these things isn't mutually exclusive, but one prompts far more concern than the other.
This isn't even just about Japan. For instance, I'm not overly worried about Turkey downplaying the Armenian genocide, I'm concerned about the tensions between Greece and Turkey, and Turkey's actions in Syria.
No, but see above as to why I'm more concerned about actions in the present than actions in the past.
To clarify, the idea that Japan refusing to apologize for past attrocities has hindered diplomatic relations isn't an idea that reassures me, but it's not an idea that overly bothers me either.
Again, I'm not overly concerned with what happened a century ago, I'm more concerned with what's happening RIGHT NOW. If we were living in the 1930s, then I might have been worried about Japan. But since we're living in the 2020s, even confining this just to Asia, Japan apologizing for war crimes is low on my list of priorities.