Hi! I hope I understand your question correctly. A SyntaxError in your own script normally means that there’s invalid code in there that Python cannot interpret – so this is unlikely to be a problem in Prodigy.
I think in your case, the problem is here:
html_render = <input type="checkbox" value="test"> Test
html_render is supposed to be a string containing HTML markup, but it’s missing the quotation marks around it:
Alternatively (and if you’re writing JSON), you could also escape the double quotes with a backslash, e.g. type=\"checkbox\".
If you want to use checkboxes, you might also want to try the choice interface? See here for an example recipe. The question and each option can all take "html" instead of "text", so you can also use custom formatting there. For example, a choice task could look like this: