Hi Lisad,
I'm a SALT.
In very precise terms, fifth centile means that 95% of children would do as well as or better than your daughter did on that assessment, in a similar testing situation. So it's not really strictly true to think of it as 'out of a hundred children x would do better', though this is a common misperception and something I didn't understand until I was at MSc level.
If it is a CELF result, there are some whizzy additional stats for children with ASD in the manual which means that these can be adjusted. Do you have subscores?
The way I use the CELF is to look at it in terms of processing.. so a lot of verbal kids with ASD type difficulties have discrete areas of strength e.g. they typically do better on some subtests, like recalling sentences, which looks at memory span and echoic ability than they do on others. There are also subtests they do poorly on that reflect their specific processing style vs 'understanding of language' per se.
I am generalising massively here, of course - massively - just wanting to point out that sometimes reports read a particular way and are not really reflective of the real-life communicative profile.
I will say, to my shame, that I used to write these horrendously wordy Doom doom doom reports and not really consider the massive impact they would have on a family. I can't quite believe how little I understood of the way it can come crashing in on you when something is not quite right with your flesh and blood.. and I would not write a report like that now before consulting carefully with the family on what they wanted from the report and having a conversation about whether they felt that what I saw in a test result matched their understanding of their child's difficulties.
Tests are a tool, but only a tool.. and though they are tremendously useful for 'high stakes' assessment (the kind that has the potential to relax purse strings), they're not really to be taken too seriously in the context of real life. They can be a window into some difficulties if they are interpreted skilfully and with a proper conversation with the people who really do communicate with that child on a day to day basis, but don't see your child reduced to numbers.
If you would like to ask anything further about the assessment that I might be able to help you with, please let me know.