Looking at the strings in this card reminds me a little bit of looking at the IIe diagnostics card dump:
I reckon the IIe diagnostics card must inhibit the onboard rom and replaces the rom from D000-FFFF.

The two rom chips are 8k in size, but one of the chips has FFs in 4k of them.

Code
hexdump -C EPROM18B.BIN 
...
00000fd0  06 51 05 52 07 52 05 53  06 53 07 53 05 54 07 54  |.Q.R.R.S.S.S.T.T|
00000fe0  05 55 07 55 09 51 0a 51  09 52 09 53 09 54 09 55  |.U.U.Q.Q.R.S.T.U|
00000ff0  0a 53 0b 52 0d 51 0e 51  0d 52 0d 53 0e 53 0e 54  |.S.R.Q.Q.R.S.S.T|
00001000  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  |................|
*
00002000

4k of FF chars
then it looks like it continues from S.S.T to U.U.W

hexdump -C EPROM19B.BIN 
00000000  0e 55 0d 55 02 57 02 58  02 59 02 5a 02 5b 03 5b  |.U.U.W.X.Y.Z.[.[|
00000010  06 57 05 58 07 58 05 59  07 59 05 5a 07 5a 06 5b  |.W.X.X.Y.Y.Z.Z.[|
00000020  09 57 0a 57 09 58 09 59  09 5a 09 5b 0a 5b 0c 57  |.W.W.X.Y.Z.[.[.W|
00000030  0c 58 0c 59 0c 5a 0c 5b  0e 58 0d 59 0e 5a 0e 5b  |.X.Y.Z.[.X.Y.Z.[|
00000040  09 15 53 16 52 17 51 18  51 19 52 1a 53 1b 53 1c  |..S.R.Q.Q.R.S.S.|
00000050  52 1d 51 1e 51 0d bb 56  bc 56 bd 56 be 56 bf 56  |R.Q.Q..V.V.V.V.V|
,,,

Code
> f = io.open("EPROM19B.BIN")  a=f:read("*a") print(a:len()) for i=0,a:len()-1 do c = a:byte(i+1) if (i%64 == 0) then print() io.write(string.format("%4x",i)..": ") end c = c % 128 if c>=32 and c<=126 then io.write(string.char(c)) else io.write(".") end if c==0x1b then io.write("ESC") end end print()
8192
...
 a00: E...** APPLE ][e KEYBOARD TEST PROGRAM **. ALARM WILL SOUND AND 
 a40: CORRESPONDING.CHARACTER WILL FLICKER IF KEY BOUNCES.   CONTROL '
 a80: C' WILL EXIT THIS TEST..  MATCH LOW RESOLUTION CHARACTERS.  WITH
 ac0:  THOSE ON LORES SYMBOL TABLES.     PRESS SPACE BAR TO CONTINUE..
 b00: CURRENTLY TESTING MEMORY AT $D000-$FFFF... LOOP #..SUSPECTED FAI
 b40: LURE AT LOCATION F.   APPLE ][e DIAGNOSTICS.   1983 APPLE COMPUT
 b80: ER INC..   Enter the Letter of.    the Desired Test..<P>  PROCES
 bc0: SOR TEST.<R>  READ ONLY MEMORY TEST.<M>  RANDOM ACCESS MEMORY TE
 c00: ST.<C>  CHARACTER SET TEST.<K>  KEYBOARD TEST.<V>  VIDEO TESTS..
 c40: <L>  LOOP ROM RAM AND PROCESSOR TESTS.<S>  SPEAKER TEST..SPACE B
 c80: AR TO RETURN TO MENU...      SPEAKER TEST PLAYS 5 TONES.        
 cc0:   INCREMENTING FROM.          LOW TO HIGH PITCH.. MICROPROCESSOR
 d00:  IS OK...   >MICROPROCESSOR IS BAD<..   >INPUT/OUTPUT UNIT ERROR