Image appearing after text

It sounds like you're using a Paragraph text element, which allows you to set the text inside the element to appear with an animation like a typing or a bounce or a swing effect. (They're neat effects!)

Unfortunately, the Paragraph element has no way of knowing how long its effect will take to complete and no way of communicating that "completion time" to the page as a whole. It simply applies the effect to whatever text you've added in. And in the case of the Type effect, adding more text means it will take longer to complete the effect.

So, as you've suggested, the only way to set the image to appear after the Type effect has shown all the text to set this up as a time-based Show action. That could be based on the Page loading, and an easy way to set that in a Claro page is to use the Timeline below the stage. Here's an article on the Timeline feature as a whole and here's a lesson on using the Timeline to Show an element on the page based on Page Timing.  

You can also set the timing up from the Interact tab. Under the Triggers button in the Current Page section is the option Is Loaded. This would be the route to use if you're working in a Flow Page since the Timeline feature below the Stage is not available for Page-based timing in Flow (because Flow pages often have more scrolling, so timing to page loading can mean that elements are being shown out of view to your learner.)

Hope this helps!