Sorry for the late response. I have been travelling.

I don't really understand what it is that you want to do with the 'Alef G' example. This looks like a re-ordering operation, which is not something that OTL is designed to do. Also, OTL is applied to glyph runs that are typically demarcated by script boundaries, so trying to affect substitutions involving Hebrew and Latin glyphs is unlikely to work.

Similarly, with the number substitution you will run into the problem of glyph runs being demarcated by directionality, so the RTL Hebrew letters will be processed separately from the LTR numerals. If this worked in CS3, I'm not sure how.

Was the Hebrew font a non-Unicode .ttf?

ID CS3 ME handled non-Unicode .ttf Hebrew differently than in CS5 or later.

To get around the limitation John referred to, there must be a space on each side of the Hebrew string. As a type creator, make this space a zero width in order to place the non-Hebrew G besides the Hebrew.

John, I made work-arounds back in the nineties when there was no ID CS/3 ME or higher, just Quark 2.x US edition. :)

I got it to work

I had 2 problems

1. I what ever i type in brackets the text should disappear
[this text disappears when selecting medial forms]

Now it works.

2. text20 the numbers should be supirior (but in hebrew)

Now it works