In general, i18n tools for Java are quite sophisticated so with Java it won't be that much of a problem. Other environments probably require some more manual work.
Some IDEs (Intellij IDEA and Eclipse for instance) allow you to extract strings from your source code and externalize those into a property file. However, those tools aren't perfect and will likely still miss some strings. So, at least some manual work will still be necessary.
We have convinced the customer that it is better to get the English version into production first, get market feedback, get some traction, and then proceed with i18n+l10n.