The old i18n requires the base name and keys to by explicitly set.
This is not the case for e.g. /modules/samples/dialogs/samplesFieldShowRoom/form/tabs/tabSwitch/fields/switchComposite/options/.
New i18n generates set of keys but if i18nBasename is set, then it takes the first key from the set and tries to translate with old i18n. This can break especially after fixing MGNLUI-3773 if the first i18n key in the set will be on another position (more supported keys would be added).

The easiest solution is to set labels for these options. Proper fix would be to remove i18nBaseNames and hardcoded labels so we can test new i18n in the integration test where is this dialog used.