Try to remove TD_AUTO_EXEC_NEXT qaualifier.
Your design intent is not clear from your description.
This is my understanding of what you are asking.
You intend to continuously bounce between adc_buffer1 and adc_buffer2 indefinitely.
Your question deals with the ISR is called on every sample transferred(?).
It appears you are using DMA_1__TD_TERMOUT_EN for TD and TD. If ISR_DMA_DONE_ADC is being generated from the 'nrq' output of DMA_1, then you should only call the ISR after 32 samples are transferred. Now the ISR will continuously repeat since the end of TD calls TD to start everything over. It sounds that you are looking for a terminating event.
You need to determine the conditions of your terminating event. Once you determine that, you can stop ADC_SAR_1. This will stop the DMA.
I'll try to help further but I will need more information.
PS: user_342122993 suggestion about removing TD_AUTO_EXEC_NEXT makes sense if you want your terminating event for the DMA to be after TD or TD. Note: This will only stop the DMA not the ADC_SAR_1 conversions.