Ada
It has a lot of really nice features for creating data types and has amazing static analysis during compile time.
But all the tooling around it is absolute crap making using the language unbearable and truly awful. If it had better tooling I could see that it would have taken a decent chunk of development away from C and C++
Embedded systems run into this a lot, especially on low level communication busses. It’s pretty common to have a comm bus architecture where there is just one device that is supposed to be in control of both the communication happening on the bus and what the other devices are actually doing. SPI and I2C are both examples of this, but both of those busses have architectures where there isn’t one single controller or that the devices have some other way to arbitrate who is talking on the bus. It’s functionally useful to have a term to differentiate between the two.
I’ve seen Master/Servant used before which in my experience just trips people up and doesn’t really address the cultural reason for not using the terms.
Personally I’m a fan of MIL-STD-1553 terminology, Bus Controller and Remote Terminal, but the letters M and S are heavily baked into so much literature and designs at this point (eg MISO and MOSI) that entirely swapping them out will be costly and so few people will do it, so it sticks around