Even though it possible does not mean it makes your job faster or easier. Imagine a case like this. If property's name in the object inspector show "nama" ("name" in Indonesian), how to change the property's value in runtime?
Button1.Name: =''a ';
or
Button1.Nama: = "a";
If both are possible, your program more difficult to read because you have to read the documentation (LCL, fcl, etc. ..) in 2 (or more) languages. If the first option is chosen, will be very difficult because the name property in the object inspector is different with the code editor (and you end up using 2 languages). if the second option is chosen, then you must translate the source code you get from a third party into your language.
Please remember, lazarus is tools for developers, not end users. Software for the end user need language support, but Lazarus did not (probably need to menus or error messages but not for programming language).