loose-skip-innodb-flush-log-at-trx-commit and loose-skip-sync-binlog options results:

./mtr --suite galera_sr --force --big-test --max-test-fail=0 --parallel=auto --mysqld=--loose-skip-sync-binlog --mysqld=--loose-skip-innodb-flush-log-at-trx-commit

On SSD galera_sr.galera_sr_cc_master has failed.

And on HDD Only 3 tests have failed:
galera_sr.galera_sr_kill_all_norecovery
galera_sr.galera_sr_large_fragment
galera_sr.GCF-1018

Status as of 26.03.2019 on Server 10.4.4 (debug build from 10.4 branch).
The following tests failed:

SSD laptop:
galera_sr.GCF-1018

HDD desktop:
galera_sr.galera_sr_large_fragment (due to timeout 15 mins)
galera_sr.galera-features#56

And there is another one sporadic failure that passed during outstanding run:
galera_sr.GCF-597

Status as of 04.04.2019.
Server debug build from 10.4 branch, commit ba7d33a898d383f19f18733e6c25b029cdc304f3.

SSD:

Without parallel=auto: all passed.

With parallel=auto. Sporadic failures:
galera_sr.galera_sr_mysqldump_sst
galera_sr.GCF-1060

HDD:

Without parallel=auto and with default testcase-timeout=15 mins. Failures:

galera_sr.galera_sr_large_fragment
galera_sr.galera_sr_many_fragments
galera_sr.mysql-wsrep-features#8
galera_sr.GCF-1043A
galera_sr.GCF-1043B
galera_sr.GCF-867
galera_sr.galera-features#56
galera_sr.galera_sr_insert_select
galera_sr.galera_sr_small_gcache

With parallel=auto. The suite run does not reach its usual end. The last output is:

Attempting backtrace. You can use the following information to find out

Status as of 15.04.2019.
Server debug build from 10.4 branch, commit e4c5551964f398ebbe2b1b34fef028eff6f22fbe.
Tests run on SSD.

Without parallel=auto.
All 85 tests were successful.

With parallel=auto. Sporadic failures:
galera_sr.galera_sr_mysqldump_sst
galera_sr.GCF-623

Remaining failing test cases reported separately.