Hybris SmartEdit or Spartacus approach?

I need clarity on the best use of SmartEdit and Spartacus Storefront.

e.g. If I have to create an Offer page (new page template) and add two different banner components, should I update SmartEdit CMS or Spartacus code?

You need to define the CMS in backend (SAP Commerce) and frontend (Spartacus). Then, you use SmartEdit as a WYSIWYG editor.

In SAP Commerce, you define the CMS (template, page, components).

In Spartacus, you get the page/CMS via OCC (web services) and display/render the CMS. If you created new CMS types and did not reuse existing CMS types (e.g. CMSParagraphComponent), then you need to customize Spartacus to render the new components properly.