As far as I know, the txt2al converter is supposed to work by creating delta files from modified and original objects and converting those into AL files. In my current test, i added a function to the Codeunit 80. Afterwards the Codeunit was exported via Powershell and the new syntax tag.
The same was done to an original Codeunit 80. These 2 txt files were used in the compare Objects Powershell command to create a single delta file.
The new delta file includes the new function and is run through the conversion tool.
Sadly nothing happens. No Errors and no file.
The Files used are attached and the NAV Version used is CU8 for the Objects and NAV Environment. Both the CU 8 and CU9 Version of the txt2al Tool were tried to the same effect.
Modified CU80 NAV 110.txt
Chronus CU80 NAV 110.txt
COD80 Delta File.txt
Maybe because in AL there is nothing like a Codeunit Extension Object?
Indeed, currently there are only Table or Page Extensions. For all other objects the whole modified object must be offered in new syntax to txt2AL (so you can only use your own, not those of the base app).