Hello,
If you are the customer of a Level 30 Engine Manufacturer, you will receive the default weakness, rather than what the manufacturer sets.
For example:
If the L30 manufacturer sets ACC/FE as their engine attributes, the customer will still receive ACC/BRA as their attributes.
This was recently adjusted by the developers and was mentioned in this changelog post.
https://igpmanager.com/changelog/111
"Fixed customers of engine manufacturers inheriting the custom weakness attribute set by the manufacturer at any given circuit. This was never the intended behaviour. Customers were supposed to receive the default weakness and not the custom one."
I am sorry for any inconvenience this may cause.
I hope this helps you. If not, please reply and I'll try to be of further assistance.