I yesterday got my English Mastery done because of advice that @OnslaughtDom has given. Definitely recommend bypassing the unfair advantages the AI has by starting out with the max amount of resources, then quickly facilitate your base by building all the buildings you need and immediately bum rush the AI.
You can also put your map settings to ‘revealed’ and no fog of war to reduce any risk of not finding the AI and not orchestrating your attack effectively.
I do agree with you on using the advice on how to bypass the unfair advantage. I do see where this type of Hardest level would be needed to satisfy the expert players in AoE4 but by making it the only way to completely all masteries is a failure from my own business point of view. When looking at the percentages of expert players vs non- expert players or new comers to the franchise, you come to a much larger percent of players that would never be able to complete the game. Key note there is most of those that can not complete the game due to what they see as an impossible setting will not be looking to try AoE titles in the future.