Test Code:
<Text>V3 Only: {t('v3test', { count: 0 })}, {t('v3test', { count: 1 })}, {t('v3test', { count: 2 })}</Text>
<Text>V4 Only: {t('v4test', { count:0 })}, {t('v4test', { count:1 })}, {t('v4test', { count:2 })}</Text>
<Text>Both: {t('bothtest', { count:0 })}, {t('bothtest', { count:1 })}, {t('bothtest', { count:2 })}</Text>


Translations:
{
    "bothtest": "{{count}} V3 item",
    "bothtest_one": "{{count}} V4 item",
    "bothtest_other": "{{count}} V4 items",
    "bothtest_plural": "{{count}} V3 items",
    "v3test": "{{count}} V3 item",
    "v3test_plural": "{{count}} V3 items",
    "v4test_one": "{{count}} V4 item",
    "v4test_other": "{{count}} V4 items"
}