Replace Values in Column dynamically

Anonymous , just for fun

let
    stu_format = (txt) => "#{" & Text.Replace(txt, ",", "},#{") & "}",
    cats = List.Buffer({""} & cat_table[Value]),
    format = Table.TransformColumns(student_table, {"Categories", (x) => Text.Format(stu_format(x), cats)})
in
    format

and the one with dictionary

let
    cat_dict = Record.FromList(cat_table[Value], List.Transform(cat_table[ID], Text.From)), 
    result = Table.TransformColumns(
        student_table,
        {
            "Categories", 
            (x) => ((cats_list) => Text.Combine(
                List.Transform(
                    cats_list, 
                    (w) => Record.FieldOrDefault(cat_dict, w)
                ), 
                ", ")
            )(Text.Split(x, ","))
        }
    )
in
    result

the long way round:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("JYq5DQAgDMR2Se2CI7yzRNl/DRA0lmU5wkS1JOzTaXQGk8VGBel1VdS+IUf3zgM=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Categories = _t]),
    CatTable2 = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("VY89D8IgEIb/C3MH8dtVY3Vp0sRN0gFPIiSUS4Cl/76HZ0Mcn4e7916UElI0otPZJjE0SqyJLtaMLuU4fc2GTG+n5IAntsRnhx4//L4jvkLlPfGd1qs5lAS6UM2RM+Dv0InkE+uQXJFoowlgmeWS/FuQpWyLmF/aezal7M3EUQfmUrYzbwcuGDal7gNh+cAwAw==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [ID = _t, Value = _t]),
    ChangedType1 = Table.TransformColumnTypes(CatTable2,{{"ID", Int64.Type}}),
    #"Added Index" = Table.AddIndexColumn(Source, "Index", 0, 1, Int64.Type),
    #"Split Column by Delimiter" = Table.ExpandListColumn(Table.TransformColumns(Table.TransformColumnTypes(#"Added Index", {{"Categories", type text}}, "en-GB"), {{"Categories", Splitter.SplitTextByDelimiter(",", QuoteStyle.Csv), let itemType = (type nullable text) meta [Serialized.Text = true] in type {itemType}}}), "Categories"),
    #"Trimmed Text" = Table.TransformColumns(#"Split Column by Delimiter",{{"Categories", Text.Trim, type text}}),
    #"Changed Type" = Table.TransformColumnTypes(#"Trimmed Text",{{"Categories", Int64.Type}}),
    #"Merged Queries" = Table.NestedJoin(#"Changed Type", {"Categories"}, ChangedType1, {"ID"}, "CatTable", JoinKind.LeftOuter),
    #"Expanded CatTable" = Table.ExpandTableColumn(#"Merged Queries", "CatTable", {"Value"}, {"Value"}),
    #"Removed Columns" = Table.RemoveColumns(#"Expanded CatTable",{"Categories"}),
    #"Grouped Rows" = Table.Group(#"Removed Columns", {"Index"}, {{"Categories", each Text.Combine(_[Value],", ")}}),
    #"Sorted Rows" = Table.Sort(#"Grouped Rows",{{"Index", Order.Ascending}}),
    #"Removed Columns1" = Table.RemoveColumns(#"Sorted Rows",{"Index"})
in
    #"Removed Columns1"