Change multiple values of multiple columns at once

I don't think that in this case the accumulated function is the most suitable, in terms of efficiency.

Try the following diagram. The only difficulty is selecting your 24 columns.
I used the list.range function to select 3 columns starting from the index {2} that is the third one, but this is just to give an example.
In your case, where are the 24 columns or how can they be identified by the name?

let
    Origine = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("Jcm5DQAwCATBXi4mAWxwL4j+2zBPMlppI8Ag8DJKcQ1JgU5ZRi3MZ3XqMp7CHzI/", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Colonna1 = _t, Colonna2 = _t, Colonna3 = _t, Colonna4 = _t, Colonna5 = _t]),
    cols=Table.ColumnNames(Origine),
    colnames=List.Range(cols,2,3),
    ttc=Table.ToColumns(Origine),
    mycols=List.Range(ttc,2,3),
    lt=List.Transform(mycols, each List.Transform(_, (e)=>Text.Combine({"ABC-",e})) ),
    tfc=Table.FromColumns(lt,colnames)

in
    tfc

Or, perhaps even better, the solution proposed by wdx223_Daniel

    Origine = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("Jcm5DQAwCATBXi4mAWxwL4j+2zBPMlppI8Ag8DJKcQ1JgU5ZRi3MZ3XqMp7CHzI/", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Colonna1 = _t, Colonna2 = _t, Colonna3 = _t, Colonna4 = _t, Colonna5 = _t]),
    cols=Table.ColumnNames(Origine),
    colnames=List.Range(cols,2,3),
    trv=Table.ReplaceValue(Origine,null,null,(x,y,z)=>"ABC-"&x, colnames)

in
    trv