Hello there, @millermasako ...
I'm not sure I have a complete answer for you, but for clarification, are you using the Canvas ePortfolio feature that is detailed in these Guides?
The reason I ask is because around October of 2019, it was announced that Portfolium has partnered with Instructure to offer ePortfolios. (This is different than the Canvas ePortfolios.) You can learn more about Portfolium by visiting the Portfolium User Group here in the Community. You may need to check with your school's Canvas administrator or Online Learning / eLearning department to see if they have talked with their assigned CSM (Customer Success Manager) at Instructure to see if Portfolium would be something that could be added to your school's Canvas environment. So, getting to your question, it may be possible that Portfolium would have better search capabilities than what Canvas ePortfolios might have. Check out these Guides: Portfolium Network - Table of Contents.
I hope this information will be of help to you, Masako. Please let Community members know if you have any other questions about this...thanks!