The timeline adjustment node on the Color page is designed specifically to affect the whole timeline. The easiest way to affect the timeline but not title elements is to place an adjustment layer on a track between all your titles and the clips underneath. Apply the Halation effect to the adjustment layer and it will affect everything below the adjustment clip. This is the easiest way to create an affect across the whole timeline with the ability to exclude certain clips simply by repositioning them above that layer.
The other way which plays into my usual deliverables is to export a textless version and drop that into a new timeline and add all the text elements before outputing the texted version. The Halation is baked into the textless and the text is unaffected.
Third method is to edit your textless timeline into a new timeline, with the text then added. This way you can go back to the original timeline and any changes are then translated in the new timeline.