Another common issue is templates is with the syntax [[:{{{1}}}|{{{1}}}]], where {{{1}}} is a page title that might be prefixed with a colon. This is often found in templates like {{softredirect}} or {{main}}.
I'm afraid the simplest solution is: {{#ifeq:{{padleft:|1|{{{1}}}}}|:|[[{{{1}}}]]|[[:{{{1}}}]]}}
This generates a normal link is the parameter {{{1}}} starts with a colon character, and a colon-prefix link otherwise.