Sounds to me like everyone here (apart from you) is scared of being accused of being racist. The whole racism thing has gone mad in my view and of course I agree with the basic tenets, but it doesn't mean that we can't be critical of people from other minority ethnic groups. She also sounds highly incompetent and trying to put the blame on you is despicable, but her incompetence will show through I'm sure of it. It demonstrates that she is very insecure in the job.
Is she from Zimbab by any chance, or maybe some other part of Africa or African/Caribbean ethnicity. I was a sw for many years and whenI retired I worked independently as a sw and worked with many sws from different cultures, mainly the ones I have mentioned. They were like anyone else, some wholly competent and others woefully inadequate. I did notice that one female sw tried to "play the race card" as this one is doing, to cover up her incompetence. I don't know which authority you work for, but this was Birmingham City Council who were realy struggling with 40% vacancy rates and many Zimbabwe social workers were taken on and in fairness to them, they struggled with the different culture, and had managers who either did not have the time or competence to ensure they became competent.
The language thing is ridiculous and she must be challenged - she clearly has tunnel vision and her own agenda. Am assuming the children were born here, and she is advocating for them to be placed with a black family who speak their mother tongue (which the children will not understand) - totally crazy. The children need a family who can meet their needs, and it is policy now I believe that consideration should be given to placing black and Asian children with white carers, rather than waiting for the right black family, which may never emerge. Hopefully the fostering panel will see the distorted thinking here, but your link worker must stand up to this crazy notion, and if she won't then you must do it!
I think you need to challenge her and anyone else who is not supporting you. Criticism of black or Asian people does not imply racism and those who think that are very muddled in their thinking.
In the UK we live in a multi cultured and multi ethnic society and clearly people need to be able to recognise that and be comfortable with it, but sounds like your sw has a hige axe to grind.....of course same race placements are the ideal, but it has to be the right kind of same race placement to meet the needs of the children, not simply because they are of the same race.
Stand up to them OP!!