In the latest AVRDUDE 6.3.0 for Arduino mingw32 the AVRCONF file contains some errors and some items are missing.

It concerns the latest AVR8X series with UPDI interface.
In the common section for the ATTiny and the common section for the ATMega processors the "USERSIG" is always the same size.

This is not true. The UserSig memory is always one extra page of EEprom memory. The correct values for both the USersig Size, PageSize and Readsize are:
 
For all AtTiny and AtMega 2xx 4xx 8xx, 16xx: 0x20 (32 Bytes)
For all AtTiny and AtMega 32xx and 48xx: 0x40 (64 Bytes)

In the common fields for all types the id bytes are part of the "Sigrow" memory, read-Only 0x100 Bytes at 0x1100, but only 27 bytes are used. The first 3 bytes are defined as "signature", with the ID number. This is correctly mentioned. The remainder is mentioned as "prodsig", also correct, but not verry usefull.

A Meaningfull addition can be: (all fields here ar read-only)
"sernum" 10 bytes 0x1104
"sernum0" 1 Byte  0x1104
"sernum1" 1 byte  0x1105
"sernum2" 1 Byte  0x1106
"sernum3" 1 byte  0x1107
"sernum4" 1 Byte  0x1108
"sernum5" 1 byte  0x1109
"sernum6" 1 Byte  0x110A
"sernum7" 1 byte  0x110B
"sernum8" 1 Byte  0x110C
"sernum9" 1 Byte  0x110D

"osccal"     4 bytes 0x1118
"osccal16"   2 Bytes 0x1118
"ocscal16m0" 1 Byte  0x1118
"osccal16m1" 1 Byte  0x1119
"osccal20"   2 Bytes 0x111A
"osccal20m0" 1 Byte  0x111A
"osccal20m1" 1 Byte  0x111B

"tempsense"  2 Bytes 0x1120
"tempsense0" 1 Byte  0x1120
"tempsense1" 1 Byte  0x1121

"oscerr"     4 Bytes 0x1122
"Osc16err"   2 Bytes 0x1122
"osc16err3v" 1 Byte  0x1122
"osc16ett5v" 1 Byte  0x1123
"osc20err"   2 Bytes 0x1124
"osc20err3v" 1 Byte  0x1124
"osc20err55" 1 byte  0x1125

The last improvement is also to mention the fuses by name.
The fuses are now named as memory "fuses" and the individual fuses are mentioned as "f0" .. f8"
A good addition would be to have duplicate entry's for the fuses
with the official names: 
"f0" duplicate "WDTCFG"
"f1" duplicate "BODCFG"
"f2" duplicate "OSCCFG"
"f3" duplicate "FUSE3"
"f4" duplicate "TCD0CFG"
"f5" duplicate "SYSCFG0"
"f6" duplicate "SYSCFG1"
"f7" duplicate "APPEND"
"f8" duplicate "BOOTEND"

hope this contribution is usefull.
Hannes Bulk, Utrecht, Netherlands