Hi,
More close-up shots of the actual fruitbodies would be helpful. but what can be seen does seem to be what would be expected, with nothing that would cast any doubts
In my experience, other Lachnellula species that have been recorded on Larix in the UK don’t have sufficiently similar characteristics to be readily confused with L. occidentalis .
Some sources do suggest smaller maximum spore size, (e.g. Fungi of Switzerland suggests a range of 12-17µ x 3.5-5µ), although spore size & shape does seem to be markedly variable in this species. – But what you’ve got here looks OK to me. 
Regards,
Mike.