Check only whois at major registrar websites.
Like here https://www.dynadot.com/domain/whois.html?domain=radiationshield.com
You can see it it there that it was registered back in 2001 and was not dropped after that.
I think it directly depends upon the quality of the portfolio one have and that depends on when you have stated domaining, how much knowledge you have acquired and how much time you have taken while reaching to 1000 domains.
With passing time a domainer become more mature and would inherently...
Outbound is generally less of a hit and more of a miss case. It mostly depends on the name and its niche. If you have decent names in the right niche you might get sales. I have few successes this year.
Why can not you share their details? If there is no mention of "refund after sale" in their TOS then they do not have any right to do this. If you mention them here there is a possibility this can be resolved or at least let them know about this thread.
Let us know who they are so we can stay...
These are IDNs (International Domain Names) and they do have value if you know about them well and they exist because to enable foreign letters and characters (for non-english speaking people) to be typed in their own languages (like Japanese, Chinese, etc.).