Since you are relating two taxonomies via the content pages to which they are applied, you need to range through the relevant content pages, build a slice of the related terms, remove the duplicates, then range through the resulting slice.
{{ $s := slice }}
{{ range where site.RegularPages "Params.sdlc_phases" "intersect" (slice "a") }}
{{ range .GetTerms "jtbd_processes" }}
{{ $s = $s | append (dict "RelPermalink" .RelPermalink "LinkTitle" .LinkTitle) }}
{{ end }}
{{ end }}
{{ $s = uniq $s }}
{{ range $s }}
<a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a><br>
{{ end }}