I've narrowed this JIRA ticket to the primary purpose of the report: SAP HANA as a common database platform in Spring's JpaVendorAdapter mechanism, with a wider overhaul planned for 5.1 there.
As for the two side improvements of the pull request - namely detecting all database product name variants and introducing a HanaSequenceMaxValueIncrementer -, I'm in the process of dealing with them as part of #21101 for 5.0.5 and 4.3.15 already.
HANAColumnStoreDialect is indeed the correct default. The SAP HANA column store is generally preferred over the row store as it offers more features as well as other advantages. The HANARowStoreDialect should only be used in special cases if there is a concrete application requirement that can't be fulfilled by the HANAColumnStoreDialect.