LP5562: question about clock

Part Number: LP5562

Hi, 

My customer is having question about the clock configuration about this part. 

They connect CLK_32K to ground but not sure if an external 32K clock is required in program execution engine mode.

Below is their main questions: 

1. Whether the led could be controlled via execution engines without CLK_32K ?
2. There is any impact (such as power consumption) without CLK_32K if execution engines work use internal clock ?
3. What is the use case requiring an external 32K clock being as a must?

Please let us know if further information needed. 

Thanks a lot.