The dictionary and language used within Symphony is based upon the individual machine's settings, not Symphony itself.
Select what language is being used by following these steps:
1. Navigate to Regional Language Settings from your machine's settings and check what language is selected (Figure 1):

Figure 1 Region & Language
Note: In this scenario, the language used is English (United Kingdom)
2. Update your settings to the language of your choice.
3. Once complete, navigate to Administrative Language Settings and in the Administrative tab, confirm the Language for non-Unicode programs matches the language chosen in step 2 (Figure 2):

Figure 2 Administrative Language Settings
4. Finally, navigate to Advanced keyboard settings and ensure language in the Override for default input method also matches the language chosen in step 2 (Figure 3):


Figure 3 Override For Default Input Method
5. Restart your machine to ensure any changes made in steps 2-4 take effect (Figure 4):
5. Restart your machine to ensure any changes made in steps 2-4 take effect (Figure 4):

Figure 4 Restart Prompt
6. Once your machine has restarted, log in to Symphony and test that the dictionary and language is working as expected (Figure 5):

Figure 5 English (UK) Language