Answer

If you mean Ratnaprabhasuri, Jain tradition uses that name for more than one figure, so there is not a single timeframe. One tradition places the Upkeśa Gaccha Ratnaprabhasuri in the 6th–5th century BCE; some summaries give 527–443 BCE, and other traditional accounts place him around 465/457 BCE after Mahavira’s nirvana. ( en.wikipedia.org)

A different Jain author with the same name, Ratnaprabha Sūri, belongs to the 12th–13th century CE; one scholarly reference dates his work to 1181 CE (Samvat 1238), while other summaries describe him as mid-13th century CE. ( peachv.org)

And if you meant Ratnaprabhā in Jain cosmology, that is the name of the first lower world/earth, not a monk. ( jainqq.org)

Explanation

So the name “Ratnaprabh” can point to different Jain figures, and the timeframe depends on which one you mean. The early date belongs to the legendary lineage of the Upkeśa Gaccha, while the 1181–13th century CE references belong to a later Jain scholar-commentator. ( en.wikipedia.org)

Spiritual Understanding

In Jain tradition, such lineage names preserve the memory of dharma, teaching, and samyaktva across generations. When a name appears in different centuries, it usually indicates different ascetics or ācāryas with the same revered name, not one continuous lifetime. ( en.wikipedia.org)

Takeaway

The safest summary is: Ratnaprabhasuri appears in both very early traditional chronology and much later medieval chronology, depending on which Jain figure is meant. ( en.wikipedia.org)