CY14B108K is an 8 Mbit, x8 nvSRAM with RTC. Last 16 address locations (0xFFFF0 to 0xFFFFF) have been allocated for storing the RTC data.These last 16 address loactions are not writable until write "w" bit is set to "1" in the flag register @ location 0xFFFF0 before writing any data bytes in the RTC registers. Most of the RTC registers store data in BCD (Binary Coded Digit) format, therefore a few bits in some RTC registers are always set to a "0" and can't be programmed with the user data.
Actual data memory (SRAM for storing user data) in CY14B108K device is 0x00000 to 0xFFFF0. To check whether RTC update are correct or not, you can write the following data byte and read back. If you don't clear the "w" bit to "0", you can read back the same data you have written otherwise if you have cleared the "w" bit to "0" then you will find Second register (0xFFFF9) updating, if the crystal is connected across X1 and X2 and it is oscillating.
0xFFFF0 - 0x02 -Set the "w" bit
0xFFFF1 - 0x20
0xFFFF2 - 0x00
0xFFFF3 - 0x00
0xFFFF4 - 0x00
0xFFFF5 - 0x00
0xFFFF6 - 0x00
0xFFFF7 - 0x00
0xFFFF8 - 0x00
Log report sent by you also shows that data read is failing for locations 0xFFFFE0 to 0xFFFFEF which is not likely to happen since its part of user memory. Please try writing data (0x55 or 0xAA) again only in memory locations 0xFFFFE0 to 0xFFFFEF, read back and verify whether failure is repeating?