may we use more than 8 buffers or arrays in an indecator or EA ?
Buffers are a special type of array only used in Indicators. You can't use more than 8 of them in an Indicator. You can use more than 8 Arrays in Indicators, Scripts or EAs . . . but an Array is not a Buffer.
More info here: Transferring an Indicator Code into an Expert Advisor Code. Indicator Structure