Thank you very much for your feedback. Please tell me where the black screen bug appears? Can you please describe in more detail and send us a save to the discord channel. https://discord.gg/RUXBmYJh
We have auto-saves at every location change, if you have a specific save that didn't load, send it to discord, we will check.
Regarding the full walkthrough. We have a post on patreon giving a link on full walkthrough guide. And also in the game in the quests section, you can click on the hints for completing each quest