within auto-completion, CT fails to remember phrases comprising a short word, e.g "of" like in "letter of intent".
Is there any way to change it without creating a fragment memory for such a phrase?
First I would check Auto-completion settings in Preferences > Workflow.
"Start at" default value is 3 characters, so "of" is not used in auto-completion. You would need to lower it to 1, I think.
Same for "Word length" (minimum character length of words to be processed by the Auto-completion function.) = Default is 7, this would mean lowering it to 2?
Of course, two-word hints should be enabled.
Second, while I'm not sure in which extend this can be useful for auto-completion suggestions, there is also the Function words threshold (%) in Preferences > Memory.
CafeTran filters out frequently occurring words which do not need to be translated into the target language as single fragments. In this field you can set the default frequency of occurrence of the words in the source text above which the program treats them as function words and they are omitted by the Auto-assembling function.
You could try to raise that threshold to let more function words be used in auto-assembling and suggestions.
If tweaking Auto-completion settings does the trick, I wouldn't touch that Memory/Auto-assembling setting, though.