Question to my application with the SPS Server profile

First what I want to have: My application must advertise for a few seconds, triggered by an external interrupt input. Then the device should go the extended deep sleep, till the next trigger. The application should run in a SPI flash memory, during the development phase. Nice to have will be the SUOTA and the battery service. But it is not so important in the moment - I think, this are not too big requests.
What I have done: I took the SMARTTag_reference application. In this application, I switched off all the services; I have reduced the advertisements to a fixed interval l and duration. I start the advertisements by an external trigger and I built in the SPS Server service, like in the SPS service application. UART1_RTS I switched to P06 because of SPI_EN on P03. I delete the buzzer function. I have loaded the program in the DevKit from Murata with LBCA2HNZYZ-TEMP-D-MU. There the application is running in the RAM, for developing, I know. The result: With a BLE scanner on my tablet, I can see the device advertising , I can connect to the application and I see the 4 SPS Services / Characteristics. With the DSPS application on the tablet I can connect, but I cannot send and receive information, the same is on the terminal in smart snippets. The SPS_device and the SMARTTTag standalone worked well on the Murata DevKit.
And now my question: I see that “app_ble_push” will send, when I send chars from the terminal. I visualized it with a toggling LED. Yu must know, these are my first steps with DA14580. What influence will have the HEAP sizes in da14580_config? Why are they different between the both applications? How far can I reduce the different parameters of TX_BUFFER and RX_BUFFER? I only must send and receive few bytes. Toggling of my LED begins earlier, when I reduce the parameters. My next step could be to debug by J-Link. According to what should I look then? What do you suggest? What shall I do next, what should I check? In the moment I am a little bit helpless – The DA14580 is very interesting for us, because it is very small, ideal for our wearable application. I hope someone will have an idea. I ever thank you in advance.