You can combine (concatenate) 2 CSbuilders into one. Here is an example:
B4X:
Dim cs1, cs2, cs3 As CSBuilder
Dim strvar As String ="Soccer is my passion"
cs1.initialize.Color(Colors.Red).Append(strvar & CRLF).PopAll
Dim strvar2 As String ="I miss it amid the pandemic"
cs2.initialize.Color(Colors.Blue).Append(strvar2).PopAll
cs3.Initialize.Append(cs1).Append(cs2).PopAll
EditText1.Text=cs3