And while inspecting their websites, I couldn't find their impact factor. is this sign of low quality or what ? Knowing that these are Thomson indexed journals. Thanks
First things first, Thomson Reuters no longer manages impact factors; they sold the business to Clarivate Analytics.
Clarivate Analytics is not an index; they are a business. They manage multiple databases, such as ESCI (Emerging Sources Citation Index) and SCIE (Science Citation Index Expanded).
To have an "official" impact factor, you need to be indexed by the SCI (Science Citation Index). If you are indexed by SCI then you are in some sense "indexed" by Clarivate Analytics, but the converse is not true. The journals you mentioned are not indexed by the SCI, therefore they don't have impact factors.
Does this mean they are low quality? Not necessarily, e.g. it's possible for a new journal to not have an impact factor simply because it takes time to be indexed by the SCI. But it's certainly not a good sign.