1. A computer-implemented method of validating translated files for inclusion in an application being developed, comprising: a computer system sending a translatable file having externalized content in a single base natural language to a plurality of other computer systems, wherein said externalized content is external to code of said application being developed; in response to a generation of a first translated file including a first translation of said externalized content into a natural language other than said base natural language by another computer system included in said plurality of other computer systems, said computer system receiving said first translated file from said other computer system; in a simulation environment, a processor of said computer system simulating a loading of said first translation of said externalized content into a user interface of said application at a runtime of said application and simulating a presentation of said first translation of said externalized content in said user interface at said runtime, by calling one or more functions included in said application, without an actual presentation of said first translation of said externalized content in said user interface, wherein an execution at said runtime of said one or more functions displays said externalized content in said user interface; said computer system determining whether the simulating of the loading of said first translation of said externalized content into said user interface and the simulating of the presentation of said first translation of said externalized content in said user interface by said calling said one or more functions indicates an error condition that causes said application to stop running at said runtime; based in part on said error condition being indicated by said simulating of the loading of said first translation and said simulating of the presentation of said first translation, said computer system: determining said first translation of said externalized content includes a syntax error that causes said error condition, generating a report including an identification of a portion of said first translation of said externalized content that includes said syntax error and an error message that is generated by said application at said runtime in response to said error condition, and initiating a correction of said syntax error by sending said report to said other computer system, wherein said syntax error includes at least one of: (1) a first key included in said first translated file is not matched with exactly one corresponding first value in said first translated file, said first translated file being a first property file including first key-value pairs including said first key and said first value as one of the pairs; (2) a second key in said translatable file is not in said first translated file, said translatable file being a second property file including second key-value pairs, one of the second key-value pairs including said second key; and (3) one or more placeholders in said first translated file are not matched to respective one or more placeholders in said translatable file, said one or more placeholders in said first translated file and said one or more placeholders in said translatable file providing variable substitution by being filled in with actual values by said code of said application at said runtime; based in part on said error condition being indicated by said simulating of the loading of said first translation and said simulating of the presentation of said first translation and in response to a completion by said other computer system of said correction of said syntax error included in said first translation of said externalized content and a generation by said other computer system of a second translated file including a second translation of said externalized content which includes said correction of said syntax error, said computer system receiving said second translation of said externalized content which includes said correction of said syntax error; and based in part on said error condition being indicated by said simulating of the loading of said first translation and said simulating of the presentation of said first translation and in response to said receiving second translation of said externalized content which includes said correction of said syntax error: said computer system simulating a loading of said second translation of said externalized content into said user interface of said application at said runtime and simulating a presentation of said second translation of said externalized content in said user interface at said runtime, by calling said one or more functions, without an actual presentation of said second translation of said externalized content in said user interface; and said computer system determining whether said simulating of the loading of said second translation and said simulating of the presentation of said second translation by said calling said one or more functions indicates said error condition that causes said application to stop running at said runtime; and based in part on said error condition not being indicated by said simulating of the loading of said second translation and said simulating of the presentation of said second translation, said computer system at said runtime presenting said second translation of said externalized content in said user interface without causing said application to stop running at said runtime; and based in part on said error condition not being indicated by said simulating of the loading of said first translation and said simulating of the presentation of said first translation, said computer system at said runtime presenting said first translation of said externalized content in said user interface without causing said application to stop running at said runtime.