You may ask Wavecom to confirm 64BK minimum erase block or you can read datasheet of flash used in Wavecom modules. Generally you can treat A&D as a simple file system: a cell as a file with random read (adl_adInfo) and senquential writing only. You do not worry about how to erase (delete in A&D) cell detail, you just call adl_adDelete in your app when the cell is not needed, similar to delete a file in other OS. However, deleting cell does not mean the cell space is released. You have to call adl_adRecompact to release the cell space. I guess adl_adRecompact does erasing processing. All A&D operations will be failed within low level interrupt.
If accessing flash in your app is critical, I suggest you use external flash, such as AT45XX, ranging from 4MB to 16MB with serial (compatiable SPI) interface and byte read/write capability. Therefore, AT45XX can be used as a circular buffer with a great flexibility. However, A&D is not. Frankly A&D implementation might be based on improper design or the designer could have knowledge limitation when proposal of A&D specifications.