I installed bluepy on my Raspberry Pi4 and got it to work.
Your issue is the struct.unpack_from() function. Have a look at the following documentation.
https://docs.python.org/3/library/struct.html
Because Arduino uses 32-bit floating point (4 bytes) you need to use an 'f' instead of an 'e'. Because you have three of them you need to use 'fff'. And just to make sure we specify little-endian because we use an ARM Cortex processor which uses little-endian byte order.
print( struct.unpack_from( '<fff', value ) )
It will not, but using 16-bit UUIDs for your own services and characteristics is against the Bluetooth rules.