Well, I have found another discussion in the forum here, which mentions that there is not such a thing like a config option to switch to v4 and the only option would be to use the old and unmaintained v2 sources. Well, this is not a future prove alternative for me. Hence my question is answered.
You can go to a legacy version of Teiid that includes OData V2 before [TEIID-3754] Remove OData V2 implementation of the Server - JBoss Issue Tracker such as Teiid 9.0.6 Maven Repository: org.jboss.teiid » teiid » 9.0.6 and try your scenario. If it works and you have sufficient motivation, then the v2 implementation could be forward ported to Teiid latest.
thanks for your feedback! However, as it seems that there is an undefinable amount of work involved in both solutions:
1. Working around the OpenUI5 issues client side and keeping Odata V4 or
2. Switching to OData V2 and doing the porting there and using the stable OpenUI5 implementation.
I think the more future proof solution is to solve issues on client side. I hope I will get some support from the SAP guys on these topics. Unfortunately their help forum seems to be not that greatly maintained like the one here. So I will first see how far I come with it.