How does Hanna's illiteracy affect the mood of The Reader by Bernhard Schlink? How does it affect the readers's experience and view on Hanna?

It is important to note the allegorical significance of Hanna's story. Bernard Schlink asserts that Hanna's illiteracy is a metaphor for individuals who had "forgotten their moral alphabet during the war"; they had forgotten the very foundation and basics of human decency, causing them to perpetrate and be complicit to mass murder.
Mood, as a response to Hanna's illiteracy, is engaged with later in the novel upon Michael's realization that Hanna is illiterate after one of the court sessions. When readers are given this information, their general response would be one of sympathy. Clearly, it would be difficult having to hide this from others for her entire life. Hanna is constantly ashamed and limited by her illiteracy, and if others discovered this, her shame would increase significantly. While reading the novel, one feels sorry for Hanna, though still angry at her complicity—particularly when we learn that Hanna did not open the church doors, causing the deaths of hundreds of prisoners, because she did not want to disobey orders and let the prisoners escape.
Hanna's illiteracy is associated with her downfall and, in a way, her partial redemption. She is given a life sentence based on a report that she did not write. Moreover, Hanna would have been better equipped to defend herself had she been able to read the court documents and the survivor's memoir that had been used to charge her. After Hanna's death, Michael visits her prison cell and learns that she had spent years reading Holocaust literature after learning how to read. This gave Hanna a deeper perspective on the atrocities she was part of, specifically her participation in the selection process at Auschwitz and the deaths of prisoners in the church. This makes readers more sympathetic toward Hanna and even sadder over her death. In the end, Hanna was fully aware of her crimes, and this awareness may have contributed to her suicide.
Hanna is such a complex and fascinating character. She undoubtedly loves Michael, yet she abandons him and causes him lifelong emotional trauma. Their relationship is beautiful in a way, but it is tainted by the fact that his many hours spent reading to her is reminiscent of the children that read to her in Auschwitz before they were sent to their deaths. Despite knowing her crimes, Michael records himself reading books for years, sending the tapes to prison and helping Hanna become literate.
I would say the general moods associated with Hanna are sympathy, sadness, anger, and indignation. She took a job as a guard at Auschwitz because she could fulfill its responsibilities without reading and writing, unaware of her part in a genocide that killed 6 million people across Europe. Was she evil for her participation in mass murder, even though she later understood and regretted her actions? Can she really be forgiven and understood for the lengths she went to hide her illiteracy? It depends on the reader and their interpretation of evil.