Hopefully there is not anything "fundamentally" wrong ... it should have been quite straightforward after the Symbol-accounts were defined.
E.g. in February I found my XYM-account from the account explorer with the importance 0.017282 % and everything seemed to be ok.
Now I cannot acces that XYM-address in the XYM-wallet, tho gave the correct mnemomic.
And the account is not found from the
http://explorer.symbolblockchain.io/accounts/NCEW6I* ... just saying "This account does not have a public key yet".
Was there some XEM limit for Opt-in accounts? E.g. if the account had too few XEMs, then for it is not created the XYM-account?
(Before the snapshot I moved most of account's XEMs away, coz had unidentified problems with Win10 and the XYM-wallet)
Edit: if there has happened some error, then here is one guess/solution: the reason was in the loop, where some items were removed/skipped

As a reward I could receive the silver coin fund's content

I hope You didn't move Your xem before the snapshot happened? It needed to be in Your opt-in account at the time of the snapshot! I think the minimum was 100 xem, so if You didn't have at least 100, the account was not recorded in the snapshot.