I will differ with you to some extent. Ella seems to have been rather obtuse when it came to the marriage of her niece, Marie, to Prince William of Sweden. And Queen Victoria wasn't the only one who was against the marriage. Their father, Grand Duke Ludwig, was very much against it also. And Alix of Hesse's unsuitability for being empress was not so unknown as you maintain. When she made several visits to Russia to visit Ella, the comments from Russians who met her were invariably negative and critical. Ella could have asked around if she had wanted to get opinions. And there were people in Hessen who could have told her a thing or two about Alexandra's suitability. I suspect politics had as much to do with it as romance, having a sister married to the heir and thus one-day empress.
Queen Victoria maybe had a grasp of Ella when she wrote that if Ella was truly happy in her marriage with Serge, then why was she always having to say she was happy. People who are really happy, the old queen remarked, don't have to go about justifying it to themselves or to everybody else. She suspected that maybe not was as it seemed to appear.
And as to Ella's understanding,she seems not to have realized the situation in Russia. When she went to see Serge's assassin in prison, she asked him why he had done such a cruel thing to a good man,and he told her a few truths. She re-acted with saying she hadn't realized such things existed.
And she saw what Serge was doing in Moscow, especially to the Jews, and remarked they would probably have to pay for it later, but like all the Romanovs she shrugged her shoulders and then went on about their merry ways. Maybe she wasn't exactly obtuse, but like most of the Romanovs she kept her blinders on.
In was only after 1905 that Ella began to become a truly caring human being and devoted herself to a truly Christian life.