Conversion of ltcx to ltc seems to be possible, and it basically represents saving one to another using the original program that uses them, LTC - Linquisitic Tree Constructor. It is unlikely any other program would be capable of this conversion.
Convert LTC syntactically analyzed text XML file to LTC syntactically analyzed text.
We found one software available in the database for this conversion.
Microsoft Windows software - convert ltcx to ltc on Windows
A free program for creation of linguistic syntax trees from text
Convert from ltcx file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.