Hi,
1. That is not exactly how it works. Synonyms does not mean it will display the same results at all. Synonyms only ensure, that multiple words are treated the same. It does not mean, the plugin will search for “luces” instead of “luz” when typing in “luz”, it will still search for “luz”.
If you want to change words from the input to completely replace them use this custom code instead. That will yield the exact same results.
2. Internet explorer in general is no longer supported by WordPress, IE users should be prompted to use Microsoft Edge instead. If you still need to use internet explorer, then switch the plugin scripts to legacy mode and disable the scrollbar script: https://i.imgur.com/bvo9EIb.png
That should work with Internest Explorer.
