Currently since 1.x and still in 3.x there is a limitation of multi hierarchy in automatic parameter lookups.
Many public component modules found online (including forge) utilize parameterized classes but if someone is using multi-hierarchy merging via deep or deeper merge_behavior this doesn't work and is known/documented limitation.
Problem is this is fine probably for 90% of people but those people who are utilizing multi hierarchy lookups or different hiera backends (yaml/eyaml even at same hierarchy level) are now required to open pull requests to change:
While this is doable it's a work around for a long time known limitation.
Can we correct the limitation so it works within the parameterized class?