Took me a long time and it was the silliest thing. My solution:
hla = capture.add_high_level_analyzer(extension_directory=os.path.join(os.getcwd(), f'SPI_ADC_HLA'),
name='SPI_ADC_HLA', input_analyzer=spi_analyzer, settings=None)
It would be really helpful if Saleae team could provide examples for their automation API. Could have saved some time.