>The site use ISO-8859-8 encoding.
>For example the word (in ascii value) 247 / 225 / 232 / 228 is cut and
>left only the 228 char.

Swish-e has an algorithm to recognize what is possibly a word, and will 
ignore words that do not match.
It knows about regular chars, consonants, vowels. (see check.c, and your 
configuration).

My guess is that the character 225 is not a recognized letter. 

Make sure to add regular hebrew letter in the string WORDCHARS in config.h 
Also check BEGINCHARS and ENDCHARS and recompile.

See also if the following constants are defined like here:
#define IGNOREALLV 0
#define IGNOREALLC 0
#define IGNOREALLN 0

These values will enable/disable the constraints on vowels, consonants and 
digits inside words. 
IGNOREALLV => ignore all vowels words
IGNOREALLC => ignore all consonants words
IGNOREALLN => ignore all number words.
0 = deactivated
1 = activated

Stephane